I am doubtful ti is a driver conflict. I still got the drivers for my 3870 installed even though they haven't been loaded in months it still doesn't cause me issues but I am someone who makes sure that my system works before hand. As for you chances are that you may have a bricked card but rule that out by testing your card in another machine.
^+1 test in another system if possible.
i wish i have another comp to test out...
Ask a friend??? Most people got lots of them or if you are like me then I suggest that you look into RMA while sorting potential software issues first.
Does the 8800 GT still work?
If you don't see any POST screens, which doesn't require any graphics card driver to be loaded to be seen, then there is a problem with the graphics card. Try taking it out and reseating it.
You may even try troubleshooting by using both video cards with the 8800 GT as the primary assuming there are enough PCI-E supplementary power connectors.
the 8800 gt still works. thats what im using now. i really think i could have a defected card.
RMA and that will take two weeks before you get your new card in the mail.
Only problem is I got it used. So I don't know if it's still under warranty or not.
There may still be a chance of there still being a warranty. Contact customer support and tell them about the problems that you are having with your card and see if they will help you out or go ahead for rma.