I ran into this and had to uninstall an antivirus suite that was blocking updates. Some may not want to do that but we had a clone of the hard disk ready before we took the AV suite out.
My PC keeps going into 'Downloading 1 of 3' Do not switch off your computer. This happens every time i switch it on. It then has to repair it's startup before i can access anything. When I check the history in Windows Update it shows having failed on many of the updates. The error message can show different error numbers which I can't seem to find any advice on.I am running Vista on my PC
Any ideas anyone.