Windows xp is corrupted by XP ANTISPYWARE 2010. When Win. xp opens it says 'rundll32.exe' not available.This is a dual-boot Ubuntu/XP machine. I removed the av.exe files but I cannot edit the registry. Windows XP cannot access the internet and regedit is disabled. All applications go to an 'open application with' screen which will then open some applications such as word processing but not regedit or Windows Explorer.
This bug is a really nasty one. We have had some luck with system restore, but if that doesn't work, copy the data off and reinstall the OS. Even after cleaning with several tools and verifying the bug is gone, the OS is damaged goods.