While using Dreamweaver CS4 to make minor template changes to the default Prosilver theme for PHPBB 3.06 I found a syntax error in the file known as overall_header.html

Lines 49-50:
49. <!– IF S_USER_PM_POPUP –>
50. if ({S_NEW_PM})

Here’s how I fixed it:
The problem lies on line 50, where the statement is enclosed in 2 sets of brackets. Try deleting the inner brackets leaving this ->   if (S_NEW_PM)
this also works->    ‘{S_NEW_PM}
so does this->   {S_NEW_PM}’

Having said all that I think the syntax may be unique to PHPBB3 and should probably be left intact as I have not seen any parse errors on the site I am assisting with where this is installed.