This is a problem that can happen if you select the option in Dreamweaver to Include Unicode Signature (BOM) On creating New pages or when saving, it is a PHP bug:
bug.php?id=22108
to fix the problem, Go to File -> Save As. In the Save As Dialogue box, uncheck the Include Unicode Signature (BOM) option.
you should make sure that this option is not set in Dreamweavers preferences as well.
Go to Edit -> Preferences, in the new Document section, uncheck the Include Unicode Signature (BOM) option.