Hi DM,
The GT-P5100 TV card is PCI based and the remote works via an IR cable that is actually plugged into the Card with the sensor for the remote attached to the monitor or elsewhere in view of the Remote Wand.
With this in mind MilosPZS, is the remote sensor attached correctly to the card (it hasn't come loose or been pulled out when you have moved your PC) and do you have a clear line of sight from the Remote Wand to the sensor?
Also, what motherboard and revision number are you using?