I am unable to install or uninstall any programs in Windows Vista. If I
attempt to do so, I get the following message:

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

I get this error if I try to install a program using a CD, DVD or download,
and I get this error if I try to uninstall a program from the Control Panel.

I have rebooted several times, yet this problem persists. Any suggestions?