CMOS error

[buzz]

I'm receiving an error at start-up and I need help.  First, I haven't changed my computer's configuration or updated it in several months.
The message is from a program called MegaTrends #107, error in CMOS startup.  Press F1 to run set-up or press F2 to accept defaults.
I pressed F2 and my computer ran like a pig!
I don't know what CMOS is, so before I attempt set-up I'd really like to know what caused it, and of course, what the HELL it is.
Any suggestions?  Thanks, in advance.
P.S.  I think it must be coming from DOS, but can't find the error in any books.  It prevents me from loading Windows 98 and continuing unless of course I press F1 and run like a pig.

[buzz]

I think I fixed it, maybe.  Went to "My Computer", and went through all the devices/controllers/driver.  Saw a CMOS reference "date and time".  My system was showing Jan. 1999.  How ?  I reset them and was able to re-boot.  Hope this isn't an omen.

[Bear]

Uh...Windows 98?...Perhaps you should change your socks
more often.
Good hygeine helps one meet more sharp chicks.

[Shackles]

If it keeps up and you don't feel like shelling out $$ for an updated system, try replacing the battery on your motherboard. It may do the trick.  Your computer is beginning to suffer from electrical alzheimer's disease...

[buzz]

Thanks Shackles.  Printed out all the instructions, will do it immediately.  Appreciate your help.