JP

I am unable to install any software or uninsall because Windows (Vista
Business 64bit) says to me following when trying to remove or add
software.

[Window Title]
Windows Installer

[Main Instruction]
Another program is being installed. Please wait until that
installation is complete, and then try installing this software again.

[OK]

Also, windows update doesn't work anymore and every time I shutdown
machine it tries to install pending updates from Windows Update but
they do not install.

I have tried to look Windows Processes but there is no installation
process there, I cannot find any running installations. Is there some
register settings that prevents further installation?

Any advice highly appreciated.