Unit has the latest Nov 09 software and loader.

Whilst in the Schedule and navigating using the up down arrow buttons, and when a recording starts at the exact same time, my system reboots.

This has happened twice now, and on return after the boot the scheduled recording does not auto start as it has been logged as a failure.

Has anyone else encountered this problem?

Interesting! In exactly the same situation I have had the box freeze (not reboot) when doing that just as a recording is ending.