I've got an older Acer 6920G which has an odd problem.
In bios or dos it will sit forever and have no trouble at all, however when it loads Vista it powers off and on before vista has even loaded correctly. I've fitted a brand new hard drive to it too, then tried a windows 7 install. It gets to the microsoft logo to begin installation and then it powers off and on again. Occasionally it will actually load to desktop but very rarely.
I removed the fan and heatsink, cleaned and reseat
I'm currently running windows memory diagnostics on it but no errors reported yet.
Any ideas what I need to be looking at? Why does it happily load bios and even dos but not windows?
I can try a ubuntu install next if that would help any further?
Acer Aspire 6320G
Intel Core2Duo T5750 @ 2GHz
ATi HD3650 512MB graphics
3GB DDR2 5300
120GB Hard Drive