I've just been trying to fix glittertigger's new laptop.
This came with Vista and a trial version of Norton Internet Security.
Tonight, this crashed, and confused Vista so that it wouldn't cleanly boot. Fortunately, the Vista System Restore seemed to fix things.
However, this did seem to confuse Norton. Following the boot, one of the Norton services would crash. The Symantec help said to update it with LiveUpdate. This failed, claiming that it didn't understand the update. The Symantec help said to update LiveUpdate. This didn't help.
Having got fed up with this, I decided to just uninstall Norton (which is what I should have done when the computer arrived). This failed, as the Norton uninstall thought that Norton was running. Attempting to turn off Norton caused it to crash in the same way as the crash I was trying to fix. Following the Symantec help for this indicated that I should go through some steps to verify the subscription. This failed as it only had a trial subscription.
I then tried to kill the Norton processes with the Task Manager. This failed as Vista claimed I didn't have access. I enabled the Vista admin facilities and tried again. This failed again claiming that I didn't have access. I don't understand Vista.
Fortunately, after yet another reboot, Norton Uninstall decided that it would finally work. This took the better part of ten minutes just to do the uninstall.
Hopefully this has now got rid of it, so I just now need to put on a more sane anti-virus. Sigh.