So, I'm assuming this freezing issue is usually related to a faulty hard drive. Perhaps a firmware issue? Thanks for the number. I'll give them a call. I've another 1.5TB drive I'll try out tonight. Same model.
I really doubt it is the MX-1 causing the problem. Never seen a post reporting that. I put a Seagate 1.5 in my "owned" 20-700 and it did freeze up a few times, but the problem seemed to heal itself. Doesn't do it anymore. I have five Seagate drives that are on the "problem" list and yet I have had no problems with them, except for the brief problem with freeze ups on the internal drive, so it is not every drive on that list.
I'd still give Seagate a call and see if they can download a fix for you.
To get back to your original question, many things cause freeze ups. I think of freeze ups as something that can be fixed with a click of the remote and lock ups as something that can only be fixed by a reboot. And I never use the red button to reboot. Never.
Anyhow, the freeze ups can be caused by software, bad HDDs, HDMI switches, etc. No way to really answer your question. Same thing with lock ups. The lock ups are a lot more serious. They can be caused by all kinds of things.
I do think your problem is the HDD, but if you still have problems with the other 1.5, it might (probably) be the MX-1.