Computer issue? o.o...

[pyro]

Yea, I have an old Dell Dimension 2400 desktop I want to sell. But before I sell it I have to fix all the bugs. It works just fine, but whenever it comes unplugged, I get a message about the time not being set, everytime. Not sure why. But the BIOS keeps resetting on its own?
Anyone know why?
Oh, and it boots itself up as soon as I plug it in. And I have NO idea why ><...

Here are some pics.
Image 1
Image 2
Image 3

 

[TFT]

Motherboard CMOS battery gone flat

 

[pyro]

Really? I have a few, I'll go change and try it :}

Edit:

Awesome, thank you. Popped a new on in and fixed the problem, thanks alot!