me think of over heat condition which will cause many & varied snafu's.
How long since last cleaned professionally or even thoroughly at home?
Could be power supply over-heat shut down to prevent further damage?
Try removing both side covers & aiming fan inside. Does this extend time before shut down ?
Can't help you re: Linux story except if base conditions bad adding to it could only hurt?
Others may have better ideas which I welcome! Good Luck!
i was using windows xp and after it boots it stays on for 5 minutes and then turns off. I installes mandriva linux 2008 and now it doesnt turn off at all unless a boot windows any suggestions