I was having the same problem, I set up a whole weeks worht of recordings and it didn't record any of them!!! I think the problem is that the unit doesn't timer record when the power is on? Which is a bit ridiculous..? Anyone from Samsung have a solution my unit is the DVD-SH873
I can do an immediate record with no trouble but when I set up the timer record and the time comes it won't record and the red clock on the front panel flashes. This supposedly indicates that the HDD has no spare capacity but is occurring with 100% spare capacity. I've spent days on and off trying to get it to work. It's connected to a Phillips LCD TV via HDMI cable. The TV is a year or two old.

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