I have an 830 with the same problem. I ride with a Varia, Quarq and HRM Pro. As a minimum it happens once every ride, most times more than once: all sensors are disconnected. Considering that I commute a fair distance daily, that is a lot of crashes. Fortunately, in my case, within about a minute the software seems to recover and reconnect the sensors; not always though, on the odd occassion only a reset will work. Annoyingly the Varia often changes from flashing to solid mode after a crash, which is not optimal if you don't notice it.
Considering the rain we've had here in the last while I can say that the fact that the touchscreen lock does not work consistently and causes weird display issues is my top grievance at the moment.
I've kept all firmware updated to the latest at all times, the latest firmware seems to have exarcerbated the problem but that is hard to quantify.
None of the above solves the problem of course but at least now I know I'm not the only one...
