If you have the update your firmware level will be 22.214.171.124.RC6-VMB-11-C68 (Home > Help & Settings > System Info > System Info). According to Virgin Media, the box should no longer crash if watching some shows; the wake up bug has been fixed and if you press play and then OK during playing back a recording it plays faster (but the voices don't go high pitched).
There are new options in the power saving settings which at the bottom of the screen;
Connected Low Power - powers down after 4 hours but still lets you watch recordings on that box from elsewhere
Eco Low Power - box will power down after 4 hours