Monitor Problem

I have 17 inch monitor(flat screen). Ive had it for a while. Ive just recently bought a new 7600GS GT Edition. It plays fine and stuff, but today after restarting my computer, It would jam(my computer) when I clicked on the login screen, so I restarted by the off the button and when I opened my monitor it had a white streak which is taking up about 1/4 of the screen!(on the top) Ive tried everything to get rid ff it. I pluged my monitor on my other computer but same thing! Can someone help please.

Computer specs:
1GRAM
3500 AMD Athlon 64 - 2.2Ghz
190GB

My monitor model : m17gka

Thanks