The annoying thing is that I don't want it to turn off the GPSR at all... it's a Streetpilot III, by the way, and I love it to bits, even if it is a bit slow by today's standards
I've tried switching it on before I switch on the bike (1200GS), switching it on after I've powerd up the bike and switching it on after I've ridden for a few minutes... the thing will go on to battery power (or switch off) after about 30 seconds. The only thing that (sometimes) works is to stop when I get the "Switching off in 30 seconds" message, switch off the bike and switch on again and immediately hit the start button without it going through it's pre-flight check routine. I don't know what ramifications this has, but I'm sure BMW wouldn't recommend it.
I telephoned my local dealer about this and they say that there's nothing they can do at present, as BMW are working on a fix.
If I'm riding on my own, I can keep stopping and bu££ering about to get it working, but when I'm with mates, it's rather annoying.