WinTV, Nova-S Plus, Working fitst time, not after that

#1
Hi everyone,
Yesterday I bought an WinTV, Nova-S Plus, when I installed it it worked fine and signals were perfect, but while watching the screen suddenly turned black and none of channls are working, I did these things for trouybleshooting.

1, Took out the PCI card and inserted it in again, after that I got the picture bach, but after shour period of time the same thing happend, if I reinsert it, the same thing will happen.

2. I thought maby the PCI slot on the motherboad is damaged, so I took the card and inserted it into antoher PC, the same process happens (1).

3. I thought maby that PC is not working fine :) so I tested it on a third PC, the same thing happens.

Any suggestions? what should I do next? before I take the card back to shop < I don't like this one ;).

Thank you.