Can't add new categories or products

Hello,

I'm hoping someone can help me. I recently moved servers and now whenever I add a new category and then add a product to it, when you click that category in the category box you get a blank page. I've uploaded the files several times and even imported the database 3 times. I am completely baffled. Here's the link.I'm using hostmonster. if you click the iphone apps link in the categories box you'll see what I mean. I've tried everything.Thanks for your help.

If you're using 1.3.9, check your /cache folder for error messages. If not, install this , then check the messages:

**http://www.zen-cart.com/index.php?main_page=product_contrib_info&products_id=**860

I have no idea what any of this means. Please see if you can make any sense of it. My cart was working just fine before I moved servers. this is driving me nuts. thanks for your help.

[25-Jul-2010 12:39:33] PHP Warning: session_start() [<a href='function.session-start'>function.session-start</a>]: Cannot send session cache limiter - headers already sent (output started at /home2/.../public_html/includes/extra_datafiles/about_us.php:2) in /home2/.../public_html/includes/functions/sessions.php on line 108
[25-Jul-2010 12:39:33] PHP Warning: Cannot modify header information - headers already sent by (output started at /home2/.../public_html/includes/extra_datafiles/about_us.php:2) in /home2/.../public_html/includes/init_includes/init_templates.php on line 78
[25-Jul-2010 12:39:33] PHP Warning: Cannot modify header information - headers already sent by (output started at /home2.../public_html/includes/extra_datafiles/about_us.php:2) in /home2/.../public_html/includes/functions/functions_general.php on line 44