It's always happened for me when I leave my computer on for ages as well. I have no idea what the glitch is called (by Microsoft) or how to patch it. But the best way around it like you said as it's happened to me is to restart your computer. :)
I've never used it because I don't want to people to know that I'm doing that sort of shit (registering on a Habbo retro) on Facebook..
For me it's 0 - 2 scale.