[zaimbat]

Ok I found out the problem.
(How? I opened 2 admin control pannel:
- in the first I was scrolling MY style, in the other the plain one;
- every "red" style I did a diff between the two styles;
- every mod, I tried "edit tags";
.. untill I found out the problem)

This is the code, it was on the top of "postbit_legacy":

<div id="pmformdiv$post[postid]" style="display:none">
    <form action="private.php?do=insertpm&amp;pmid=$pm[pmid]" method="post" name="vbform" target="_blank">
   
    <table border="0" width="100%" align="center" class="alt1">
    <tr>
        <td align="center">
            <!-- subject field -->
            <table cellpadding="0" cellspacing="0" border="0" width="100%">
            <tr>
                <td align="left"><strong>$vbphrase[title]:</strong></td>
                <td align="right"><input type="text" class="bginput" name="title" value="$pm[title]" size="50" maxlength="85" tabindex="1" /></td>
            </tr>
            </table><br />
   
            <!-- message area -->
            <div align="left"><strong>$vbphrase[message]:</strong></div>
            <textarea style="width: 95%" rows="8" name="message" tabindex="1"></textarea>
            <!-- / message area -->
   
        <div style="margin-top:$stylevar[cellpadding]px">
            <input type="hidden" name="s" value="$session[sessionhash]" />
            <input type="hidden" name="securitytoken" value="$bbuserinfo[securitytoken]" />
            <input type="hidden" name="recipients" value="$post[username]" />
            <input type="hidden" name="fbpm" value="yes" />
            <input type="hidden" name="savecopy" value="1" />
            <input type="hidden" name="do" value="insertpm" />
            <input type="submit" class="button" name="sbutton" value="$vbphrase[submit_message]" accesskey="s" tabindex="1" onclick="divwin.hide();" />
            <input type="submit" class="button" value="Preview/Advanced Edit" accesskey="r" name="preview" tabindex="1" onclick="divwin.hide();" />
        </div>
        <!-- Do NOT remove this copyright notice or I will find you and hurt you. :) Thanks! -->
        <div class="smallfont" align="center"><a href="https://vborg.vbsupport.ru/misc.php?do=producthelp&pid=fbpm" target="_blank">Facebook style private messaging</a> by <a href="http://www.robwoelich.com/" target="_blank">Rob Woelich</a></div>
        </td>
    </tr>
    </table>
   
    </form>
</div>

I don't know why it's here. It's from an old release of "Popup Private Messaging". The 1.3 version hasn't this mod in the install guide.. probably it's a problem of the uninstall.

Anyway, THANK YOU! Really!