I left my computer on, when I went to bed when I woke up and got on it the mouse froze. So I restart it, and its says MJ Jumper Installed and under it, it says Keyboard Fuse Failed. Then there are these weird lights in the back that I never seen are going off. I have a windows XP Dell home edition.

Hi Jacqueline. It would be good to know the pc model then maybe could look up the weird lights, you may have a psu problem. The Keyboard Fuse Failed message is shown here http://support.dell.com/support/edo... (click on System Messages).

PC model?

Yes, so far we know it's a Dell but which model? Examples are Optiplex GX280, Inspiron 530 etc. The link I posted also shows PSU indicators, click on Power Indicator Codes.

On the power supply indicators there's four instead of three. The A and D is green and the B and C are yellow. I guess the model would be Dell Dimension.

I took a chance and downloaded the manual for the Dimension 5000 but the light pattern you give does not appear in the diagnostic list so no luck there. Can you be more specific on the model number? Below is a list of possibles from a Dell Wiki: Previous Dell Dimension models * Dimension 1000 Series - 1100 / B110 * Dimension 2000 Series - 2100, 2200, 2300, 2350, 2400 * Dimension 3000 Series - 3000, 3100(E310), 3100c, 3050 * Dimension 4000 Series - 4100, 4200, 4300, 4300s, 4400, 4500, 4550, 4600, 4700 * Dimension 5000 Series - 5000, 5100, 5150(E510), C521, E520, E521 * Dimension 8000 Series - 8100, 8200, 8250, 8300, 8400 * Dimension 9000 Series - 9100, 9150, 9200 Here's some info on the lights, they are not on the psu as I first thought, they are diagnostic lights: To help you troubleshoot a problem, your small form factor, small desktop, and small mini-tower computers have four lights labeled "A," "B," "C," and "D" on the back panel. The lights can be yellow or green. When the computer starts normally, the patterns or codes on the lights change as the boot process completes. If the POST portion of system boot completes successfully, all four lights display solid green. If the computer malfunctions during the POST process, the pattern displayed on the lights may help identify where in the process the computer halted.

If you don't know the model of Dell then post the service tag off the back of the tower.