Neither Firefox nor the profile manager will start. In my task manager, the process is using 50% of my cpu but does nothing. I love browsing with firefox, how can I fix this?

I've tried restarting my computer, the I tried uninstalling and reinstalling, then uninstalling, erasing all firefox files and folders, then restarting and reinstalling. I've also tried opening the profile manager to change my profile. After reinstalling a few times and trying to open the profile manager before launching firef0x, I got the firefox has crashed window and the process in the task manager is still using 50% of my cpu. The most recent expunge then re-download pops up a "file is corrupt" error and won't even install the program.