Login to your vB Admincp and click on "Settings>Options" on the side menu, then go to "General Settings" in the drop down and choose it. Now scroll down and find "Add Template Name in HTML Comments" tick "Yes" and then scroll down and save the settings. This will render the template name when you view the source of the site. Go to your site on the thread/page/posts/pm where ever this is happening and then right click anywhere in the browser screen on the page and choose "View Source". Now when you view the source you will see what templates are called in the code. The templates called are in green in the source view. This should help you narrow down the problem.
Also if you have a straggler "<" out there it will usually show all the time and be somewhere weird or look weird. But sometimes you do not always see it if you have a custom skin, it will disappear from time to time. This was a simple template coding error and can happen when a mod installs code into templates (if the developer does not check their code) or when you or someone else modifies the templates and makes a coding error. Basically you are looking for code that would look similar to this in the template. This is
JUST an example
NOT the code you need to search for:
Code:
<<a href="http://mysite.com">My Site.com</a>
Notice the double "<<" this is usually the cause of an error such as this. The correct way would be:
Code:
<a href="http://mysite.com">My Site.com</a>
See the difference? If you cannot place your URL here in this thread for help for whatever reason then you will have to actually search for this error, but as stated above if you turn on the template tags and then give us a link to your site one of us should be able to spot it and tell you where/what to edit. Otherwise its a bit hard to help with little info, kinda like trying to help in the dark when you need to see.