Contact Form 7 gives 500 error while Akismet is activated

Hello! My Contact Form 7 was giving me some issues a while back (not loading pages, etc.), but I kind of wrote it off. Today I upgraded to 3.1.3 and noticed that I was not able to activate Contact Form 7 while Akismet was activated (and vice versa).

If I try to activate CF7 while Akismet is activated, I get 500 internal error message. I have to delete the files via FTP to get rid of it. When CF7 is activated and I try to activate Akismet, I get a 500 internal error. When I refresh the page, the error goes away but Akismet is still listed as deactivated.

Any thoughts on what this could be and how I can solve it? As you can imagine, both plug-ins are crucial for a blog. Any ideas would help.