I got the same problem. It happened after I flashed the bios to the latest version in order to get rid of the problem with the battery not charging (this is well documented if you google it). I only has about 10 seconds after boot up until it would switch off. I used the 10 seconds to disable ACERFAND and voila, it was now stable. I got rid of ACERFAND and installed a1ctl to do the same thing. Guess what - got a shutdown shortly after this, so got rid of a1ctl also. No problems since.