server reboot itself

[Louis Fung]

hi, everyone,   sorry if I post it on the wrong mailing list.   I installed 3 times, give me same result. I have a testing server, installed Linux (tried Mandrake 7.0 & RedHat 6.1).  once I leave it on overnight. The next day morning, it had no screen, no video signal, I tried move mouse, hit keys on keyboard, even the numlock has no response. so, I have to reset the machine, once reset the machine, the linux boot up to "finding dependencies modules", it reboot or shutdown itself.   here is some spec of the server. Intel L440GX+ motherboard (GX chipset) Dual Intel P3 550 CPU 2GB SDRAM (512MB x 4) on board scsi is AIC-7896 2x Seagate Cheeta ST39103LW (Ultra 2 - LVD)   any suggestion will be appreciated. thank you for your time.   Louis