hi guys,
when i just start up the com (win xp), when it load the ms-dos it pop up cmos error , of cos i went to my advance bios and set it however if i shut down my com, follow by shut down the main switch of the plug after 30 min , when i back to switch on com again, it pop up again (it seems to appear so long if i shut down the main switch, any solution? i had reformat before however it does not cure it .

Get yr cmos battery replaced. It seems your bios cannot keep yr cmos setting. If replacing battery does not solve your problem, then is yr bios problem.

yeah sounds like a battery maybe. another way to check is set the time and date in the bios. and then restart computer and check if the date and time is same or has it been reset.