It's not a new install, or modules or anything like that... i just posted something one day and got all these errors and its in my downloads, main and a few other sections.... heres what i get when i changed them, i had too change line 304 because the other one didnt do anything.

Warning: head(themes//theme.php) [function.head]: failed to create stream: No such file or directory in /home/ryan/public_html2/php/header.php on line 31

Warning: head() [function.head]: Failed opening 'themes//theme.php' for inclusion (include_path='') in /home/ryan/public_html2/php/header.php on line 31

Fatal error: Call to undefined function: themeheader() in /home/ryan/public_html2/php/header.php on line 47