Desktop

Using the jumpers

Unplug, or switch a jumper on the motherboard (for "switching a jumper" I mean that you find a jumper that joins the central pin and a side pin of a group of three pins, you should then unplug the jumper and then plug it to the central pin and to the pin on the opposite side, so if the jumper is normally on position 1-2, you have to put it on position 2-3, or viceversa)
To find the correct jumper you should read the motherboard's manual.
Once you've located the correct jumper, switch it (or plug or unplug it, depending from what the manual says) while the computer is turned OFF. Wait a couple of seconds then put the jumper back to its original position.
If you don't have the motherboard's manual, you'll have to "bruteforce" it... trying out all the jumpers. In this case, try first the isolated ones (not in a group), the ones near to the BIOS, and the ones you can switch


Removing the battery

If you can't find the jumper to flash the BIOS or if such jumper doesn't exist, you can remove the battery that keeps the BIOS memory alive. It's a button-size battery somewhere on the motherboard (on elder computers the battery could be a small, typically blue, cylinder soldered to the motherboard, but usually has a jumper on its side to disconnect it, otherwise you'll have to unsolder it and then solder it back). Take it away for 15-30 minutes or more, then put it back and the data contained into the BIOS memory should be volatilized. I'd suggest you to remove it for about one hour to be sure, because if you put it back when the data aren't erased yet you'll have to wait more time, as you've never removed it. If at first it doesn't work, try to remove the battery overnight.
Important note: in laptop and notebooks you don't have to remove the computer's power batteries (which would be useless), but you should open your computer and remove the CMOS battery from the motherboard.

If you have a bootable cdrom, used it and {re)install the OS.
If not press f8 when you see "starting windows..)
use the option to go to the command prompt.
Then do:
cd\windows
edit win.ini

you should have
"run="
"load="

exit

and then edit system.ini
you should have "shell=explorer.exe"

exit

and reboot.

Leopold