Have you run a registry cleaner?
It's funny to me that I've been using Windows update since 1998 on 31 computers and never had the first problem with Windows update, yet I see numerous posts like yours here all the time. Have you by any chance made changes to the registry or run registry cleaners? I wish I understood this better, but anyhoo here're some things you can check.
First visit the MS web site for this problem at
http://support.microsoft.com/kb/818018/en-us . This will let you run Fixit and give you information about other things to check.
Also check out this link from a MS engineer
Some other things to check.
. Get your antivirus program up to date and boot into Safe Mode. Note that some viruses can hide themselves from your antivirus program in normal mode, so you really need to scan in Safe Mode. To get into Safe Mode when you first power up, hit F8 about once a second until you get the menu and select Safe Mode. Then run a full system scan.
Microsoft has suggestions and offerings at
Forum moderator Keith has some suggestions along this line at
You can check for corrupted system files. Open an administrator command prompt and run SFC if the above doesn't help. Click START, then type CMD in the search box, right-click CMD.EXE and click Run as administrator. Then from the command prompt type sfc /scannow.
Finally if all else fails, you can check the rather cryptic system event log. To do so click Start -> Control Panel -> Administrative Tools -> Event Viewer. Once in Event Viewer click on the system log and scroll through the entries looking for those flagged "error" to see if you can find hints as to where the problem could be.
I hope this helps. Good luck.