Recently I've found that my PVR will not record anything, even if I manually set the recording. I go into the guide and push the red button to record a program, or link a series, and the box goes red. When I come back later to watch the recorded program its nowhere to be found! I have plenty of space on the hard drive, and the firmware version is 7.21. I only bought it in early June, but it was "refurbished", and so only came with a pathetic 3 month warranty. I feel like I've been ripped off to say the least!

Is there any reason why it stopped recording or any fixes you can suggest before I attempt to return it to the shop?