Lock up on Installation of Extensions

[TimeHorseOnBusiness]

I updated, and then uninstalled and reinstalled and nothing helps. Basically, I can install VirtualBox, but when I try to update to the 4.1.22 Extension Pack, it downloads just fine but then VBoxSVC.exe just locks up when it tries to install. Double-click on the Extension Pack and the same thing happens. VirtualBox just hangs! Help!