Newbie here. And likely to be a one shot. I will monitor for a couple weeks if there's followup questions or comments. I wanted to return the favor, what I learned from my problem in case it helps others. Most of the same behaviors others experienced and complained about in this forum, I found too. Overall, I've been very pleased with the unit, and would still recommend to others if it fit their need. And yes, there's lots of room for improvements CM (or the company they OEM it from) could make.
I've owned the CM7400 for about 13 months (ie just out of warranty, so nothing to lose). Running wireless, OTA (antenna), HDMI to a plasma HDTV and 5.1 surround. Only recorded broadcast shows, no vudu, or internet shows. Mildly annoyed with the small disk size soon after I got it. Regularly got msg that disk was about full, and only occasionally filled it up and couldn't record more. Unit is on 24/7.
So my problem as reported to CM: "Unit not responding to remote or front panel inputs. The green light on front blinks when making input with remote, but no action is taken. It seems locked up. Manually hold power button down to turn off, reboot, No change. Disconnect power, wait, reboot, no change. New batteries in remote, no change. sw is up todate as of ~1 month ago I checked. The unit is stuck on one channel and will not change channel, go to menu, guide, etc. Can't do anything. Power to unit has been off for ~1 week, just rebooted, no change. Help?!
Has worked fine over last year. Last week of use, response was slowing down (changing channels for example)."
CM email support wasn't very helpful (pretty lame actually). So I turned to this forum. It took most of a day reading 1800+ posts. However, I got encouragement from the posts to try some things. I was already interested in upping the disk storage and noted one guy put in a larger (internal) drive and the cover wouldn't go back on. Another added an external eSATA drive. But I had to solve this lockup problem. I popped the top cover (a little more challenging than I thought it would be) and looked around. Nothing much I could figure to do, so what the heck, I'll try unplugging the red ribbon cable from the hard drive to the PCB, and see what happens. Plugged in and turned the unit on, and after it rebooted I had all the remote functions back and working. As expected, I couldn't record anything as it said the space was full (actually, the disk was disconnected). Hmm. Power off, pIug the HDD cable back in, and lockup like before. I was looking for a way to get the unit reset to the factory settings, maybe reformat the HDD, but whenever I connected the HDD cable the unit would freeze up again. It was a catch-22. I tried numerous ways to try and get over this hurdle, but couldn't. Called CM support this time, and once again was disappointed in the answers and help provided. Nice enough guy, just no options available. Couldn't send the unit to them for repair, and on the assumption the HDD was bad, they don't offer replacement parts.
My suspicion was something to do with the HDD. The front bezel came off (again, a little tougher than I thought), and I got the small nuts that hold the HDD onto the chassis bottom off. Pried off the heatsink to see the actual drive, and removed the screws holding the metal brackets to the HDD bottom. Now I got the naked drive in my hand. I don't have access to a crash/burn PC with SATA to try connecting the old drive (Seagate 320GB, 2.5") to see if it worked or not. So I went to my local Fry's store (San Jose, Ca). Initially planned to price shop for an external SATA box, with the idea I'd plug the old drive into the external box, and use the external SATA input on the 7400 to see what happened with the old HDD. With sales help, we couldn't find a SATA in/out box, all were SATA in/USB out. They did have some external SATA box+drive combo's, but I thought they were more expensive than I wanted to spend at this point in trying to solve the problem. I realized it was going to be more difficult/costly to go this troubleshooting route with the old drive, so I took the chance on just replacing the internal disk. In my old electronic days, we called this the shotgun approach. Not quite sure of the root cause, but will try a logical/probable assumption. So I bought a 1TB Western Dig 2.5" for $85 + tax. Temporarily plugged the new HDD in last night, fired the unit up, it reset to factory settings, and voila, all's working. I've recorded a couple shows, and verified it's working as it should (more correctly, as good as it did before). I unplugged the unit this AM, put the HDD mounting hw back on, front panel back on, and left off the lid. The WD drive appears to have a thicker metal top plate (heat sink?) that may do better than the factory Seagate. But it's too thick to get the factory heatsink and lid back on (as reported in another post). I'll probably drill a bunch of vent holes in the lid over the HDD and leave the heatsink off. Don't want to add a fan. Maybe down the road will find a way to test the old Seagate to see what it's problem is. Or not..
So the short version of this verbose explanation might read: If the CM7400 doesn't respond to remote/front panel controls, resetting the unit doesn't work, unplugging doesn't work, and you're brave enough to take the lid off and disconnect the HDD cable, it might just free the unit up. You can decide what direction to take from there.