It ran for a week or so before I witnessed the first lock. After that MTBF got less and less until it got to the point where less than a minute in the machine would lock. No network connectivity, no response to keypresses, you couldn't even toggle the caps lock led on the keyboard. I tried all sorts of stuff both in the kernel and in BIOS. The syslog didn't throw any light on things either. The lock didn't coincide with any channel change actions, in fact I use it mostly for watching recordings, I hardly ever watch live TV on it.

EDIT: On re-reading your post, I only used the PVR card for about a month before getting rid. All my recent problems have been with recordings from DVB cards, although they weren't at fault. It does seem they don't like the BBC's channels on Freeview, seeking to frames is erratic and innacurate.