A few minutes after I boot up my computer it freezes. The screen remains the same but I am unable to do anything except shut the power off. I thought it was a software problem so I formatted the hard drive. I still had the same problem. I took my computer to a computer technician and had it looked over. I was told that there was no problem and it had worked fine for them. I took it home and I froze just the same as before. Later I found out that it depends on where my computer is plugged in (directly into a wall outlet or through and extension cord, and or a surge protector). If it is directly into a wall I usually don't have the problem. I am guessing that I have a power supply problem. I wonder if it is not supplying enough power to the computer anymore or something like that. Anyone's help would be greatly appreciated.