Wildman, that seems to have done the trick. Thanks a lot for the tip.
Do you use the "Safely Remove Hardware" tool in the sys tray before you disconnect? I have been out of fear of the unknown...
I don't want to rain on anyones parade but that's not the problem as my phone, and others, have the same random reboot when just plugging it into a wall charger or car charger. This "feature" popped up after the last update.
I was having this problem too - my DX would reboot whenever I plugged into USB and mounted the SD card. It happened on any OS I tried (Windows, OSX, and Linux) so it wasn't related to Motorola drivers.
I finally managed to solve it by moving all of the apps that were installed on my SD card back to the DX onboard memory. I haven't had a single USB-related reboot since doing that.
Are you running "BUMP"? It has been reported to cause this issue...