Tested yes, tested on every possible configuration no.

No 2 computers are identical. Everyone has different setups, software installed etc. Would be impossible to test them on every possible configuration

Probably preaching to the converted by now, but if you run update again there is an update that removes the offending update to put things right. It's greyed out so you can't deselect it.....

I found after doing it that windows update ran very slowly on two of the four machines in the house, but running the diagnostic tool put that right too.....:-

http://support2.microsoft.com/gp/windows-update-issu...

They should make sure their own systems work...