Are you getting 57 errors with the default vB style or a custom style you have installed?
If it's the default style, I'd disable all of your mods and then re-enable them one at a time to see which ones are causing the errors. As you find them, contact the author to correct the HTML problems with them.
If it's with a custom style, I'd contact the creator of the style to have them correct the HTML errors.
After changing the style it seems that Themeforests Ideal style was pushing out 35 of the errors, changing the style has cured those.
I also traced a few that are my own errors.
I also followed your idea and disabled VBadvanced CMS, the errors then dropped to one ! which was an empty document error.
The ten warnings that are left are : ( with explanations)
Error Line 18, Column 17: there is no attribute "property"
<meta property="fb:app_id" content="471772232864883" />
✉
You have used the attribute named above in your document, but the document type you are using does not support that attribute for this element. This error is often caused by incorrect use of the "Strict" document type with a document that uses frames (e.g. you must use the "Transitional" document type to get the "target" attribute), or by using vendor proprietary extensions such as "marginheight" (this is usually fixed by using CSS to achieve the desired effect instead).
This error may also result if the element itself is not supported in the document type you are using, as an undefined element will have no supported attributes; in this case, see the element-undefined error message for further information.
How to fix: check the spelling and case of the element and attribute, (Remember XHTML is all lower-case) and/or check that they are both allowed in the chosen document type, and/or use CSS instead of this attribute. If you received this error when using the <embed> element to incorporate flash media in a Web page, see the FAQ item on valid flash.
Error Line 145, Column 7: required attribute "type" not specified
<style>.kh99_iqts_hidden { display:none; }</style>
✉
The attribute given above is required for an element that you've used, but you have omitted it. For instance, in most HTML and XHTML document types the "type" attribute is required on the "script" element and the "alt" attribute is required for the "img" element.
Typical values for type are type="text/css" for <style> and type="text/javascript" for <script>.
Error Line 205, Column 22: there is no attribute "name"
<div id="outer" name="top">
✉
You have used the attribute named above in your document, but the document type you are using does not support that attribute for this element. This error is often caused by incorrect use of the "Strict" document type with a document that uses frames (e.g. you must use the "Transitional" document type to get the "target" attribute), or by using vendor proprietary extensions such as "marginheight" (this is usually fixed by using CSS to achieve the desired effect instead).
This error may also result if the element itself is not supported in the document type you are using, as an undefined element will have no supported attributes; in this case, see the element-undefined error message for further information.
How to fix: check the spelling and case of the element and attribute, (Remember XHTML is all lower-case) and/or check that they are both allowed in the chosen document type, and/or use CSS instead of this attribute. If you received this error when using the <embed> element to incorporate flash media in a Web page, see the FAQ item on valid flash.
Warning Line 358, Column 91: cannot generate system identifier for general entity "tabid"
?avtab" href="private.php?tabid=137">PM's</a>
✉
An entity reference was found in the document, but there is no reference by that name defined. Often this is caused by misspelling the reference name, unencoded ampersands, or by leaving off the trailing semicolon (;). The most common cause of this error is unencoded ampersands in URLs as described by the WDG in "Ampersands in URLs".
Entity references start with an ampersand (&) and end with a semicolon (;). If you want to use a literal ampersand in your document you must encode it as "&" (even inside URLs!). Be careful to end entity references with a semicolon or your entity reference may get interpreted in connection with the following text. Also keep in mind that named entity references are case-sensitive; &Aelig; and æ are different characters.
If this error appears in some markup generated by PHP's session handling code, this article has explanations and solutions to your problem.
Note that in most documents, errors related to entity references will trigger up to 5 separate messages from the Validator. Usually these will all disappear when the original problem is fixed.
Error Line 358, Column 91: general entity "tabid" not defined and no default entity
?avtab" href="private.php?tabid=137">PM's</a>
✉
This is usually a cascading error caused by a an undefined entity reference or use of an unencoded ampersand (&) in an URL or body text. See the previous message for further details.
Warning Line 358, Column 96: reference not terminated by REFC delimiter
?avtab" href="private.php?tabid=137">PM's</a>
✉
If you meant to include an entity that starts with "&", then you should terminate it with ";". Another reason for this error message is that you inadvertently created an entity by failing to escape an "&" character just before this text.
Warning Line 358, Column 96: reference to external entity in attribute value
?avtab" href="private.php?tabid=137">PM's</a>
✉
This is generally the sign of an ampersand that was not properly escaped for inclusion in an attribute, in a href for example. You will need to escape all instances of '&' into '&'.
Error Line 358, Column 96: reference to entity "tabid" for which no system identifier could be generated
?avtab" href="private.php?tabid=137">PM's</a>
✉
This is usually a cascading error caused by a an undefined entity reference or use of an unencoded ampersand (&) in an URL or body text. See the previous message for further details.
Info Line 358, Column 90: entity was defined here
?avtab" href="private.php?tabid=137">PM's</a>
Error Line 488, Column 132: end tag for "span" omitted, but OMITTAG NO was specified
?mp;"><span style = "color: Red;">Spangle</a>,
✉
You may have neglected to close an element, or perhaps you meant to "self-close" an element, that is, ending it with "/>" instead of ">".
Info Line 488, Column 94: start tag was here
?mp;"><span style = "color: Red;">Spangle</a>,
Error Line 1312, Column 202: required attribute "alt" not specified
?er" width="95" height="37" style="margin-left: 16px; margin-right: 16px;"/></a>
✉
The attribute given above is required for an element that you've used, but you have omitted it. For instance, in most HTML and XHTML document types the "type" attribute is required on the "script" element and the "alt" attribute is required for the "img" element.
Typical values for type are type="text/css" for <style> and type="text/javascript" for <script>.
Warning Line 1315, Column 83: cannot generate system identifier for general entity "fref"
?fTheTerracenet/135353099898015?ref=ts&fref=ts"><img src="images/misc/95x56/fac?
✉
An entity reference was found in the document, but there is no reference by that name defined. Often this is caused by misspelling the reference name, unencoded ampersands, or by leaving off the trailing semicolon (;). The most common cause of this error is unencoded ampersands in URLs as described by the WDG in "Ampersands in URLs".
Entity references start with an ampersand (&) and end with a semicolon (;). If you want to use a literal ampersand in your document you must encode it as "&" (even inside URLs!). Be careful to end entity references with a semicolon or your entity reference may get interpreted in connection with the following text. Also keep in mind that named entity references are case-sensitive; &Aelig; and æ are different characters.
If this error appears in some markup generated by PHP's session handling code, this article has explanations and solutions to your problem.
Note that in most documents, errors related to entity references will trigger up to 5 separate messages from the Validator. Usually these will all disappear when the original problem is fixed.
Error Line 1315, Column 83: general entity "fref" not defined and no default entity
?fTheTerracenet/135353099898015?ref=ts&fref=ts"><img src="images/misc/95x56/fac?
✉
This is usually a cascading error caused by a an undefined entity reference or use of an unencoded ampersand (&) in an URL or body text. See the previous message for further details.
Warning Line 1315, Column 87: reference not terminated by REFC delimiter
?Terracenet/135353099898015?ref=ts&fref=ts"><img src="images/misc/95x56/faceboo?
✉
If you meant to include an entity that starts with "&", then you should terminate it with ";". Another reason for this error message is that you inadvertently created an entity by failing to escape an "&" character just before this text.
Warning Line 1315, Column 87: reference to external entity in attribute value
?Terracenet/135353099898015?ref=ts&fref=ts"><img src="images/misc/95x56/faceboo?
✉
This is generally the sign of an ampersand that was not properly escaped for inclusion in an attribute, in a href for example. You will need to escape all instances of '&' into '&'.
Error Line 1315, Column 87: reference to entity "fref" for which no system identifier could be generated
?Terracenet/135353099898015?ref=ts&fref=ts"><img src="images/misc/95x56/faceboo?
✉
This is usually a cascading error caused by a an undefined entity reference or use of an unencoded ampersand (&) in an URL or body text. See the previous message for further details.
Info Line 1315, Column 82: entity was defined here
?OfTheTerracenet/135353099898015?ref=ts&fref=ts"><img src="images/misc/95x56/fa?
Error Line 1315, Column 244: required attribute "alt" not specified
?ok" width="95" height="37" style="margin-left: 16px; margin-right: 16px;"/></a>
✉
The attribute given above is required for an element that you've used, but you have omitted it. For instance, in most HTML and XHTML document types the "type" attribute is required on the "script" element and the "alt" attribute is required for the "img" element.
Typical values for type are type="text/css" for <style> and type="text/javascript" for <script>.
Can someone confirm this is the VB advanced CMS causing these errors ?