White screen on enabling modules, /admin/build/modules/list/confirm

I have having some issues with my drupal install on my webserver. I have enabled a 20+ modules without error and have now got a white scrren appearing when I try to enable or disable a module. The /admin/build/modules/list/confirm appears in my browser. I have read that this could be a memory issue and have increased my memory to 250M (just to be on the safe side). This has not remedied the issue. I have disabled and deleted my recently added modules that could have caused a conflict. I have checked my error log on my server and I am getting a lot of "PHP Fatal error: Out of memory (allocated 34865152) (tried to allocate 534281 bytes) in /home/sites/test/public_html/includes/database.mysql.inc on line 301, referer: http://www.test.com/admin/build/modules/". My server has checked this out and ran a php info test and says its all working correctly so can't offer any more support.
When a module has been enabled or disabled I can just delete the list/confirm off the end of the web address and the appropriate action has been taken so I can enable and disable my modules but just come up against the white screen every time. Does anyone have any ideas as to why it may be doing this or having/had a similiar problem or offer any advice? It would be greatly appreciated.