Yeah it would be nice if there was more of an error.
Try these steps and tell me the error.
1. Go to Admin => Global Options set the debug option to display errors.
2. As admin view someones profile and hit the ADD TO BUDDIES link. If there is truly an error adding a buddy you should be able to replicate it. Then tell me the error displayed on screen. See the email message is missing the whole explanation of what your error is. The displayed error should tell you what your server is bulking at.