Well, I got a reply from ASRock Support after 2 weeks and here's that they had to say:
Since the ouput of our system is PC signal, please the user to set the PC mode with his TV for try.
If his TV does not support such feature so far, please the user to contact TV manufacturer or vendor.
As we know, the feature may be supportted after some firmware update.
ASRock is not providing any IR receiver to any costumer;since this model does not have any problems with IR, sometimes people write in the forums ,but is not a true.
Please contact your vendor and return it for RMA.
ASRock America Support
So, it looks like they don't accept that there might be an issue with the IR Receiver and want the TV manufacturer to "fix" the problem. Well, it looks like I'll be getting nowhere with ASRock Support and if I'm not mistaken, I detect a little arrogance in their reply. Anyways, my brother-in-law wants a similar HTPC setup and I'll see if I can test the IR Receiver on his machine (when he get's it) on my machine. I'll post my findings then.
Terracotta, please provide any additional info if you get anywhere with ASRock Support.