I experinced it occasionally before, but it happens a lot more often now. Sometimes when wathcing a video of some sort, the SP4 freezes when i try to do something else (e.g. go out of fullscreen, press any button). I also have problems with sleep, that i didn't have previously. My unit doesnt seem to enter sleep. It gets really hot and the fan goes berzerk. Anyone else? This is my second SP4, and i don't want to return this one as well. I really need a working computer.