Parts of the options window not loading can be caused by a problem with an add-on. Try the procedure in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to see if it helps.

Your above posted system details show outdated plugin(s) with known security and stability risks that you should update.

• Java Plug-in 1.6.0_05 for Netscape Navigator (DLL Helper)

Update the Java plugin to the latest version.

• http://java.sun.com/javase/downloads/index.jsp (Java Platform: Download JRE)

Update the Shockwave for Director plugin to the latest version.

• http://www.adobe.com/shockwave/welcome/

You are also a few versions behind on Firefox updates with Firefox 3.6.8 (current is 3.6.11), Help > Check for Updates.
It is important to always use the latest version of Firefox and add-ons to get bug fixes and security updates.

Is Firefox written in Java??? Using the default theme. Unfortunately, I updated to 3.6.8 which caused the problem in the first place. Well, in any case I don't have any other option than to update Firefox then....

Disabling add-ons using safe mode did the trick. The funny part is, I don't have any add-ons installed..:)

Don't misunderstand me - I am greatful for the help and tips I recieved, but this is truly laughable..:)