Courtesy of this fella http://www-users.kawo2.rwth-aachen.de/~razzfazz/k750igrabber/ and thanks to this fella (via google search)
it appears there is indeed a way to stop my k800i crashing whenever I unplug it’s usb lead from my macbook pro. This little driver package disables the unused ports in the usb interface (with the sony ericsson devices). Next time I reboot I’ll confirm if it works or not, but this is good – hopefully I can recharge my phone and not risk a black curtain of doom each time!
So it appears it isn’t working (at all) but I’ll look into it again soon. Hope it might work for you.