This is the download link for the Windows Installer CleanUp Utility:http://support.microsoft.com/kb/290301/en-us
This is the download link for Dial-A-Fix which in some cases is better: http://www.bleepingcomputer.com/forums/t/160132/how-to-use-dial-a-fix-to-repair-windows-internals-problems/
By the way: in some cases this error is caused by malware. These freeware programs are recommended for additional scannings and malware removal:http://www.superantispyware.com/http://www.malwarebytes.org/
In order to get these programs into your PC you'll probably need to reboot into safe mode with network
. The moment your PC starts to wake up after the reboot command you begin tapping the F8 key - tap - tap - tap. Keep tapping. Login as administrator when the welcome screen pops up. When you get a black screen with some options on it - use the arrow keys to navigate to the "with network" option. Then start IE and go to the sites and download the programs.
Safe mode is very likely to be able to bypass what ever it is that's blocking your downloads right now. It usually does.
Edited by ePost, 08 January 2009 - 09:17 PM.