powers up but nothing happens

[Guest]

I recently installed a new graphics card, upgraded to XP, and installed a new
HD to my computer. Then I transferred some files from my old HD to the new
one. Everything was working perfectly. Then I took the computer home from my
mom's house and on the way home the CPU slid from one side of the car to the
other hitting the door. Got home connected everything and started it up.
Everything was fine I signed in to the desktop and was getting ready to open
a program when the screen went black. THe power was still on but there
weren't any lights on the front of the cpu. I had to hold in the button to
shut it down. Then I tried again...7 more times... and each time it would
power up and go through the 1st startup screen and the 2nd, but then it would
do the same thing. The fan still runs and I took the cover off to see if
anything had come loose. One of the black and white wires(that leads to the
power button) was loose so I pushed it back in. Still nothing. PLease if
anyone has a clue that would be super.

I have already confirmed everything is connected correctly and firmly.

 

[Guest]

also i have unplugged the memory and graphics card and replugged them in and
got the same thing. Then I pulled the data and power to the drives and
restarted and got this msg: Disk boot failure, insert system disk and press
enter.