run disk cleanup and clear all temp folders, go here and download windows installer clean up utility:
Description of the Windows Installer CleanUp Utility
Run it to see all those installers which have been stored.
If there are any programs who's installers have stalled without getting completed AND if they are listed there, remove them.
WARNING: If you remove installer of a perfectly installed product, you will have problems un-installing that product. So use discretion!
Re boot and fire up those installers again! Hope this helps!