Cant download critical updates.

[Rockpig]

Hi all!
I helped my brother get his Toshiba laptop going after a stop error and offered to clean it up and get it all up to date. I removed some Trojans and misc malware with AVG and AdAware. Cleaned up with the full Ccleaner treatment. Heres the problem: I went to Windows update and had trouble when trying to install Microsoft Windows Installer 3.1 - it seemed to download and then stopped when the installation was supposed to happen. I eventually found the manual installation (version 2 which fixed a bug) and saved to the desktop and installed from there. All good.
Then I tried to install the critical updates (57 of them!!) and the same thing happened - it spent about 10 minutes downloading them and then when it came to install it stopped with fail message. I just tried it with 1 and this came up:
A problem on your computer is preventing updates from being downloaded or installed.
I had a quick look to see if there was a way of saving the .exe to desktop and running the update from there but didn't find one. There must be a way to correct this on this PC. Could it be a security setting?

[Rockpig]

Just to update - another of the updates was to IE6 SP1 so I tried that - same problem but then I went to the manual download site and got the installer and it was fine - it interacted with the download site and installed the service pack. I must be missing a specific file to do with the windows update site.
Any ideas?

[Rockpig]

Ok you can all stop panicking now!
I had a look at the windowsupdate.log and found the error code that was generated down near the bottom of the (long) page and put it in my search engine and came up with the Microsoft knowledge base article 910341 which solved the problem!