About 2 weeks ago my wifes pc hp pavilliona430n was shut off accidentally when the power strip was shut off. After that the computer would not start at all. It was not getting power. I changed out the psu but since I changed it, the cpu fan keeps powering high and low,running high especially when accessing even the smallest file and at start up. It had done this in the past but not nearly as much as now. I put a monitor on it and when the fan revs high it hits the critical mark, so it says. The processor is an AMD ATHLON 3200+. I blew out all the dust around the heatsink and fan. I read that I should clean, paste and reseat the heatsink. I took off the cpu fan to clean the backside and reinstalled it. That's where the big problem begins. I restarted it and the first message was corrupt or missing hal.dll file. I'm familiar with this problem, having recently dealt with it on another system. The next error was page_fault error. Anyway, I went to do a repair with my xp disk, the whole time it's booting up the setup files, the cpu fan is running at high speed. Once the set up files are done, the computer reboots itself. I've tried safe mode, no deal, last config, nope. So now I can't even boot from the xp cd.I bought the thermal paste and I was going to do it, but once I took the fan off and saw there was dirt caked on the underside of it and cleaned it. I was hoping that just might be the problem Smiley Stranger things have happened. I even tried to undo the clips on the heatsink, but could not figure how to unlock them. Do you think that moving the heatsink a bit while trying to unclip it could have caused my problems with the re-booting? My other problem is that I'm not sure if the pc is re-booting because the cpu is getting hot or is it related to the errors i got. I'm able to f8 and choose safe mode, etc. but once the files show on the screen, it just reboots. over and over. I would really appreciate any help.