I have an HP Pavilion a6230n desktop computer that I dual boot. XP is on one physical HD, and Vista (the original OS) is on another. I had not used Vista for several years, so I performed a factory reset, re-installing back to out of the box status. The problem is that while running vista, it randomly (& instantly) powers off. No warning, no "shut-down". Just an instant loss of power.
The really odd part is that this NEVER happens when I boot into XP!!!! It can (and does) run for days-on-end on XP.
I thought it could be temperature related and that somehow Vista was causing the CPU to overheat, I cleaned the heatsink and CPU and applied fresh thermal paste. But the problem continues. The fans are all working fine and there is no dust whatsoever inside the machine.
I installed a temperature monitoring program and the CPU core temps (AMD 5000 dual core) were never above 40 C. Usual temperature was around 28 C.
The problem exists when I load Windows 7 also:. I wiped the factory HD and installed Window 7 from CD. It seemed to be running on, but after performing the Windows Updates (Important only) the problem started all over again.
Back to XP, it runs for days.
I checked the event logs and nothing obvious (or consistent) is being recorded prior to the shutdown.