Fatal error when accessing pages

When I access pages I get these types of errors randomly
Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 110 bytes) in /home2/mainsite/public_html/wp-includes/plugin.php on line 160

Bluehost had me raised the limit from 64MB to 128MB in php.ini but it did not fix the problem.

Only thing I know I did was upgraded to Wordpress 3.0.3 Not sure if that was the cause of the problem. The way I understand it it might be plugin related but my plugins were all working fine before.

Any help appreciated.