Can't Add Links? Theme Problems? Security Question? Halp ;-;

[Storyteller]

I have three major issues with my site so far,

1. Is that when I go to the admin panel and try to add a link, it gives me a "Internal Server Error" and won't let me do it. I also get that error if I try to edit existing links. However, I can delete links just fine.

2. I'm not sure why, but it won't let me switch themes.
++Edit: solved

3. The security question I set my site to use during setup (so to filter out real users from computers during registration) is gone. The answer I set works for new members to register, but they can't see the question.... I went to Global Site Settings on the admin panel, but the option to edit my security question isn't there.
++EDIT: I figured out how to make the option to edit the security question available from my admin panel (using this tutorial, in case anyone else is having the same problem). However, I am still encountering an issue with getting the question to stick. I update it, and that field just goes blank. It remains blank on the sign up page too. But the answer works just fine...?

Any ideas on how to fix these issues?
Thanks in advance!

~Story