Durabrand DPVR801 loses planned recordings from memory when put in Standby?

My DPVR801 has worked brilliantly until a couple of weeks ago. I always put it in standby at night and it hasn't had a problem until recently where it now seems to forget what I've set to record for the following week if I put it in Standby. If I leave it on and don't put it on Standby then it records OK. But it's a real pain as I had a power cut through the night last night which obviously switched it off and it then lost all the recordings planned for tonight! I've unplugged it from the mains overnight in the hope that a cold boot might reset it but to no avail. Anyone got any ideas?