Argh, Quicktimes not working, now messing up iTunes, After Effects, and even Mozilla

[MadAsHellNewYorker]

Hey folks. Ive been having a mighty weird problem, and I could really use some help with it. Ive also posted this in the computer help forum, but any advice you can impart would be awesome too :D

Im running Windows XP on a Dell. Quicktime began crashing and then it stopped opening completely. It began to effect iTunes, After Effects (both don't open and crash right away) and even Mozilla (I keep getting an error message about the quicktime plug-in). I think it may have something to do with the corrupt Quicktime files. At first, I couldn't even uninstall Quicktime, but after deleting it from the registry I finally got it to uninstall. I also uninstalled iTunes, and tried reinstalling both multiple times. I ran several registry cleaners and even the "sfc /scannow" windows utility and nothing seems to allow to be successfully run Quicktime or iTunes.

Any help DU folk? Thanks in advance.