squirrelmail php memory

Hi, I am using php to drive my webmail service (squirrelmail) and it seems really buggy. many times just clicking on links it logs me out, hangs, returns 404's etc. I think it has somthing to do with the amount of memory limited by php. Here is a sample error that appears sometimes in the pages: <snip> Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 35 bytes) in /var/www/mail.gmnet.net/html/functions/imap_mailbox.php on line 66 Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 40 bytes) in Unknown on line 0 Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 44 bytes) in Unknown on line 0 </snip> Is this something that I can fix with a php config? if so where do I start? Thanks Rick