Several months ago my ubuntu (10.04) started to freeze some minutes after boot. I didn't reboot, just get stuck (mouse, keyboard, etc.)
One day it didn't boot at all. It was dead. I tested the power supply and it was broken. I changed it (for a more powerful one) and both problems are gone. Since 3 weeks, the pc is working fine. It didn't freezes anymore.
So my question: Can the power supply affect the OS in this way? May it because of a leak of current?