Using any sort of Registry Cleaner is strongly advised against. They can (as you have seen) cause issues on your computer ranging from the simple, like this, to major (disabling CD Drives, making computer unbootable), and the "benefits" they claim to provide are very questionable. I strongly recommend that you simply uninstall this and any other Registry cleaners, system optimizers, and use the built in Windows Utilities to speed your computer up (Disk Cleanup, Disk Defragmenter, etc.). Then, after doing that, follow these steps: First, try to reset Firefox. [[Reset Firefox – easily fix most problems]]. This simple step will eliminate many Firefox problems with only one click. A few other basic trouble shooting things you can try is this: Run all Windows Updates, install all needed service packs, etc. Update your graphics driver (Firefox uses your graphics card for some rendering, and an out of date graphics card driver can cause problems. [[Upgrade your graphics drivers to use hardware acceleration and WebGL]] Update all your plugins (Flash, Java, etc.): [http://www.mozilla.org/plugincheck/ http://www.mozilla.org/plugincheck/]. Download and Install MalwareBytes Anti-Malware, run a full Scan. [http://www.malwarebytes.org/ http://www.malwarebytes.org/]. This helps check that there are no viruses on your computer causing issues. You can uninstall this program after you clean off any infections.

A reset was enough (fingers crossed)! Thanks!