Reboot and select the normal boot option. This is Windows 7 SP1 I trust? I've seen that happen with all sorts of software and it's usually a sign that something isn't stable, but the system usually recovers from it.
Try rebooting and selecting the normal boot option, usually the last one.
Then check that all your drivers and software are up to date as well as Windows.
Moved this to SecurityCenter for wider attention.