Previous installation pending W/ IE6

I have a few Windows 2000 computers where I have tried Installing IE6, but cant due to this message: "Previous installation has peding work requiring a reboot. You need to restart your computer to complete that installation before running". I havetried rebooting with no success. I also cant install any patches on these machines, I am assuming its due to this problem. When I try updating with patches it acts like its loading, but says that Windows has generated errors and will be closed.
Any idea's??? Please.....

Thanks