"enable hybrid sleep" in bios? Haven't seen that. However, there was that setting in power options in control panel but after I turned off hibernation it disappeared. It's just "regular" sleep.

I have vista business so no media center. I was thinking of safe mode as well. I'll try that later on today. However, it won't help much since I will still have to find out which service / program is causing the issue if it doesn't happen in safe mode.