I have 5 TBS6902 Dual Tuner PCIe card on each desktops running with win 7 pro 64 bits and never had a problem at all but I am going to replace all with TBS6904 DVB S2 Quad HD Tuner PCIe Cards this year ...
One of my older cards on another computer is a TBS 6925.
It did have issues where it would occasionally not be recognised by the computer and I had to uninstall the driver and reinstall it again.
Sometimes, I would physically have to remove the card and replace it to get it recognised.
It was a pain in the backside. I did contact TBS, but they were not helpful in this instance.
Remove the card and clear the pins , also clear the pcie slot, also see if some of the capacitors on the card is not looking good and needs to be replaced, get more info..., does it work on another pc!?