hard drive troubles

I just came home to my computer turning on and I see my bios then the computer is blank. I tried to boot from the cdrom and it said press any key to boot from cdrom and then the screen went blank again. I checked the bios and the hard drive is deteteced. I then switched hard drives and put a new one in and booted from cdrom and it worked fine. I then attached my original hard drive as a secondary and the screen went blank again although it was being detected by the bios. Whats going on? Anything I can do?:cry

 

Anything??

 

I have a dell dimension 2400, 2.4ghz cpu, 768 mbyte ram running windows xp service pack 3. I have been running the computer with two hard drives for a long time. I can get into the bios, as I have said, and the hard drive is read, and no matter where it is, master or not the computer screen goes blank and no unusuall sounds from the computer except that nothing seems to be loading.

When I remove that hard drive and run without it, it works fine.

 

Ya I already did that and it asks me to boot from cd and I push a key and then it goes blank.

 

Try reseating your ribbon from the mb to the hard drive at the mb. ed