Intermittant problem stalling on boot when USB stick inserted for storing EPG

Hi, VU+ DUO that gives no problems ever except when I use a usb key to store the EPG. Each night I do a 'deep standby' on the box. Next morning roughly every fourth time the box will hang on restart, the LED screen says 'restarting'. A hard reset gets over the problem but its a pain in the neck for an otherwise perfectly functioning box. I use VIX images, have used 2.2 and now use 3.0, the problem has appeared under both images, besides its most likely a boot loader problem so the enigma version is probably of little relevance. Any help or suggestions would be gratefully appreciated.

Have read on another forum to try a different USB key, I will give that a go and report back

Happened again with new usb key. Any ideas?