Re: Odd blank sections in WP admin after installing BP
It looks like you need to increase the allocated memory limit for PHP. Depending on the way your hosting company has set up the servers, you might be able to do this yourself. If you’re on a shared hosting package, they might not allow you to increase the memory limit.
I suggest contacting technical support at Rackspace and tell them about the error message. Then ask them what is set in the server’s php.ini file for the value of the memory_limit directive. If Rackspace allows for this value to be overridden by Apache, then you can easily tell php to use more memory by adding this to the very top of your .htaccess file.
### Set PHP Memory Directive ###
php_value memory_limit 60M
As a final check, make sure that your site is running PHP5. Although WordPress does run under PHP 4, it also runs under PHP 5 and that is always better.
If this is all foreign to you, then perhaps Rackspace will do it for you.