techwood tutvdtr 250gb?

My Techwood digital recorder exhibits the same problems. It sometimes crashes completely and says there's no incoming signal, or it freezes completely / jerks on playback.
Sometimes it even only records part of the selected programme.
The only cure I have found is to unplug the unit from the mains, leave for a few minutes then power it on again.
I thought it may have been a heat associated problem but after ensuring it was in a cool well ventilated area the problem still arises.
Any ideas anyone?