Try the Firefox SafeMode.
A troubleshooting mode, which disables most Add-ons.
(If you're not using it, switch to the Default Theme.)

1. You can open the Firefox 4/5/6/7 SafeMode by holding the Shft key when you use the Firefox desktop or Start menu shortcut.
2. Or use the Help menu item, click on Restart with Add-ons Disabled... while Firefox is running.
   

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before using the Firefox shortcut (without the Shft key) to open it again.

If it is good in the Firefox SafeMode, your problem is probably caused by an extension, and you need to figure out which one.
http://support.mozilla.com/en-US/kb/troubleshooting+extensions+and+themes

Nope, didn't seem to work in safe mode either, the problem in Ubuntu fixed itself, but Windows is still broken

Did you check for keyboard problems?

The keyboard is working fine, Ctrl + T works, of all the shortcuts only Ctrl + Shift + T is broken. I've already reset my configurations to default, still nothing

try the right-SHIFT key on your keyboard

Nope, that isn't working either, I also tried it with the left and right ctrl keys alternately

Do other Shift+Ctrl shortcuts like Shift+Ctrl+H work?

Yup, Shift+Ctrl+H is working perfectly

Create a new profile as a test to check if your current profile is causing the problems.

See Basic Troubleshooting: Make a new profile:

• https://support.mozilla.com/kb/Basic+Troubleshooting#w_8-make-a-new-profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)

See:

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Thanks for all the help guys, it's working again