I might actually be able to help out with this one. I was getting the same errors. Apparently this is because your wp-config.php is reading the default memory allocation of about 8meg that your host usually sets up by default. Once I edit my wp-config file to allocate 64 or 96 meg with the below instructions it popped back up fine.
Thanks for that suggestion, I wish I could do that now. But my site is hard crashed with the above error and now I can’t even get into my cPanel to delete anything. To see this go here: http://beaphotopro.com
If I CAN eventually get back into FTP or through cPanel what exactly should I delete to get the site back to normal? or do I need to wipe the site and re-install WP and Buddypress?
What does it mean that it can’t “re-declare” the ajax.php file that was previously declared?
I guess what I’m asking is: is there a way to delete or re-code something to get the site back to normal (with the default BP theme)?