I've had Mystro on my HDDVR for 2 years now and don't have any issues like that at all, at least not constantly.
I probably have to reboot it once every 3 months or more. But definitely nothing to freak out about. I can't imagine Verizon has a totally bug free set top box. Do you think they do?
That is about the results I had before Mystro. Since then nothing but problems even tried swapping the unit out. It worked for about a week or so then same problems.