I have the Humax PVR set to turn on each day at 18.00 hrs this works for a number of days then stops .
has anyone any ideas to solve the problem ?
Thanks

I have mine switch on at 10.30 and off at 1.00 every day and it works OK until the power to the machine is cut either by a power cut or manually. After that I find that the auto on/off doesn't work even though the appropriate times are still showing in the setup screen. I find I have to disable the feature completely and then re-set it to get it working again.

I used to set the timed switch on to 08.00 on BBC1 in order to overcome my habit of leaving it on BBC4 some nights before putting it in standby and then subsequently missing scheduled recordings on occasion.
I also found that it would work for a couple or three days, then stop for some reason. Never could figure it out - not related to power cuts in my case, though.

I also experience this problem and have realised it stops working after any channel updates or changes, much the same as the ITV HD timer settings bug.
You have to disable then re-enable the timed switch on to get it working again.
I have not heard any mention of the problem anywhere until now, I assume not many people use this feature.
I hope it gets fixed in the upcoming update as it is very annoying.

This appears to have been fixed with the software update

This issue was noted with my box and narrowed it down to the same as you ie the channel rescan always had me resetting the time on-off feature.

I hope you are right and they have fixed this.

YES SO FAR NO PROBLEMS