in most cases, virus also 'damage' your windows registry to prevent you to use regedit to fix stuffs and assosiating files with the virus itself.
this is how i fix it:
- download regfix.inf
- click on 'raw' and save the file on your desktop (press Ctrl+S)
- click your mouse right button (right-click) on regfix.inf and choose install (you need administrator right to correctly install this)
- restart/reboot immediately
- that's it! now you can do regedit and load task manager again.
- even if your system is clean, this wont damage your windows, coz, all those registries values are either windows default or a better values for your windows.
carry regfix.inf in your usb flash drive and rename it autorun.inf.
this way, everytime you can fix any windows registry simply plug in your usb flash disk