I recently got an upgrade to an HR44. Since it was installed a few weeks ago, it occasionally gets in a funk where any recorded show in my playlist won't play for more than 2 seconds before freezing. Hitting pause and play makes it go another 2 seconds before freezing. Switching to other recorded shows doesn't help. But live TV works fine, and if I reboot the receiver, it can play the same recorded shows just fine. But then a few days later it gets into another funk and I have to reboot.
There are several posts of similar HR34/44 freezing issues on the directv.com forums, and the advice usually given is to run the hard drive tests from the boot diagnostic menu. I did that and all the tests pass except the surface test, which gets 0.02% in, and says "Fail (300F)". On another screen it says that error means "SATA speed limited". I guess it could be a hard drive issue, but I'm dubious since rebooting makes the problem go away, at least for a few days.