My installation of Windows Vista is now so secure, it's near impossible to do things that might hurt the machine.
Anything that would raise a UAC dialog (i.e., something that requires administrator rights) will now crash the machine forcing a reboot.
Last week I was having all sorts of problems with the video-card in my laptop. It's a known problem with this particular model, and on Wednesday it died completely. However, before dying, it had crashed/rebooted my laptop around 4-5 times.
This has lead to a number of errors developing in the my installation. http.sys fails to load; UAC crashes the machine and two of the virtual machines I use for work are corrupted :-(
Once I get the morning work out of the way, I'm spending the afternoon rebuilding.