Computer Stuck Flashing Between Screens (can't do anything else) [ Edited ]

[Mellen]

Computer- Compaq Presario CQ56
Windows 7

edit: I believe I had a virus before my computer started this. I can't remember anything about the virus exspet that my Norton Internet Security said the virus was completely resolved, exsept when I check it looked like part of it was still there & it wouldn't let me try to get rid of it because it said it wasn't a threat.

When I went to start my computer up & it took me to the orange start up & the computer just flashes between that screen & a completely blank & black one screen. The orange screen includes the logo that's on the lid of the computer's & it states "click "esc" to continue to start up menu". When I get the button to work it takes me to a black start up screen with white writing. This screen says to hit "enter" in order to continue the start up process. After hitting enter, the computer takes me back to flashing between the orange & the blank screen & that's all I can do with it. It wont do anything else but flash screens & allow for the computer diagnostics to be run. Ever test the computer ran on itself has passed.

I have no idea what's wrong with it & I need to know how to go about fixing it.

edit: as of now my computer is completely dead and now wont even turn on.