Update:I've had the PVR on on for the past 2 weeks and no problems at all. I turned PVR off for 2 hours or so today and when I turned it back on, the PVR was full again.
I suppose I am not going to turn it off ever now or until the fix comes through.
I called Shaw about a week ago and they updated my PVR again because somehow my PVR didn't take the update the first time.
So far so good, I've been able to turn the PVR off, with sleep mode on for the night ( or several hours at a time ) and no problems at all.