Another permalink problem

Hi All

I have a really strange problem with permalinks. If I try and use any of the pretty links settings, (and the .htaccess has updated), all my categories and posts work fine, but the any pages return with a 404.

If I then revert to the default permalink, again all categories and pages work, but this time I do not get a 404 but I see the standard theme page, (I am using channel), that I would expect, but the content is not found and returns the following message:

Not Found
Sorry, but you are looking for something that isn’t here.

Warning: main(/home/sites/small-business-blog.co.uk/public_html/wp-content/themes/channel/searchform.php) [function.main]: failed to open stream: No such file or directory in /home/sites/small-business-blog.co.uk/public_html/wp-content/themes/channel/page.php on line 24

Warning: main(/home/sites/small-business-blog.co.uk/public_html/wp-content/themes/channel/searchform.php) [function.main]: failed to open stream: No such file or directory in /home/sites/small-business-blog.co.uk/public_html/wp-content/themes/channel/page.php on line 24

Warning: main() [function.include]: Failed opening ‘/home/sites/small-business-blog.co.uk/public_html/wp-content/themes/channel/searchform.php’ for inclusion (include_path=’.:/usr/share/pear’) in /home/sites/small-business-blog.co.uk/public_html/wp-content/themes/channel/page.php on line 24

I have tried deactivating plugins but this does not seem to work.

Anyone had similar problems, or can advise where I can look to rectify?

Thanks in advance.

Regards

Jim