strange problem with shutting down

[tarik]

ok strange problem with a customers pc.
pc shuts down almost as soon as we get into windows vista.
pc will work and run fine in safe mode.

we have checked and swapped power supplies, ram, hard drives and graphics cards all to no avail.

only thing i havent done yet is reformat but i dont believe thats the case as it happens even when i unplug the hdd and boot from a ubuntu live cd.

Have also checked all the bios settings and all seems fine.

im starting to think it could be a bad motherboard?

[KompuKare]

I assume you have tried shutdown -a?

A shutdown sounds more software to me, a reset or even instant power off is more likely to be hardware.

[tarik]

yes sorry tried that i mean an actual switch off of the pc as if power was being cut.
Temperatures are all fine and low, have also applied more thermal compound and cleaned any dust from case.

[MobileTechie]

If it works in safe-mode then I don't see how it could be h/w

[Martyn]

Originally Posted by MobileTechie

If it works in safe-mode then I don't see how it could be h/w

Was just putting that

[tarik]

Originally Posted by MobileTechie

If it works in safe-mode then I don't see how it could be h/w

this is what i was thinking originally, but then when i disconnected everything and tried booting into ubuntu same problem. computer just switches off before its even loaded.

[Martyn]

If I was going to try any hardware I would whip in a psu to test. It wouldn't explain why safe mode would work but would rule it out. Maybe you just got lucky with safe mode. Is it consistently doing it in each mode eg safe mode always ok, normal mode not, Ubuntu not?

[tarik]

changed psu already, no change

[Martyn]

Sorry didn't see that.

[MobileTechie]

Maybe working in safe mode was a one off? If not then why that happens would be interesting.

Do the logs give anything away? I.e. is the same event being logged before each shut down?