I've recently did a SystemRestore to last Sunday because my brother accidentally altered the PC in a way where it would crash in certain situations and the restore fixed the problem.
I uninstalled a mass of content, about 35gb worth, so I had to clean up the empty files and everything it put back. I manually deleted registry entries using an
online guide. Upon discovering my problem with FF's right-click menu, I undid the registry changes and it didn't solve the problem.
I've also
disabled my 'Recently Viewed Documents" folder by creating a registry value.