Cisco 9865HDC DVR Hangs intermittently in several situations

I have had a Cisco 9865HDC Contour DVR which has become increasingly problematic over the last few weeks although it has exhibit some incorrect behavior for a long time. The problems can generally be summed up as processing hangs in computer support terminology. The range of symptoms include: 1. After turning on the DVR, it won't respond to commands from the remote, sometimes for several minutes. Then, when it does begin to respond, it "plays catch-up", processing the remote commands that had been entered earlier in rapid succession. 2. When watching recorded programs, playback frequently freezes, sometimes with pixilation of the display, for long periods; trying to rewind or fast-forward frequently results in freezes and the unit again becoming non-responsive to the remote; sometimes the display just goes blank along with the clock display on the front. 3. As a result of some of these hangs, I have begun rebooting the unit (unplugging the power cord, waiting and plugging it back in) and most times the reboot does not proceed as before, sometimes taking up to an hour to completely restart. 4. In other troubleshooting, I have erased recorded and retained programs to reduce the total storage down from about 50% to about 15%; we have also cleared a number of series recordings (most of which were currently inactive anyway); nothing I have done seems to help and, in fact the problem is getting worse. As a person with many years of computer support experience, I am convinced that there is a hardware failure involved, possibly with the hard drive or disk controller, and I am ready to "bite the bullet" and take the unit in for a replacement. Of course, that means we lose everything that is recorded and the scheduled recordings but this has become an unmanageable situation. However, I thought I would ask here if anyone thinks this might be a cabling or signal issue first so I don't waste the effort. All of our cabling and signal strengths were thoroughly reviewed and "redone" by a Cox technician within the last two years.