Hard drive failed, replaced, now freezing picture - HELP!!

I recently had my RCA DVR40 drive die and since I couldn't find a base image for the RCA to download I knew the RCA and Hughes were almost identical so I took a known good image from my other Hughes SD-DVR40 unit's stock 40gb hard drive that I had pulled about 2 years ago when I upgraded it. I copied the drive over to the brand new 160gb hard drive, went through the boot process, erased everything, re-set up the satellite and tivo and now when the tivo is running it will only run for anywhere from 10 minutes to at most an hour then freezes. I thought that drive might have been bad so I returned it, bought another drive, ran diags on it and it passed, so I went through the load again and it's doing the same exact thing.

I'm wondering what it could be now?

Is there a way to diagnose if this is a power supply problem or if it's a motherboard problem?

Could it still be related to using the Hughes image on the RCA? I got the error 51 after booting initially and cleared that error so I'm thinking it wrote new signatures on the drive and should be OK, and it does show tv for a while before freezing... Should I try and find a 6.2 image for the RCA and load that?