Happened a few times now with my 935. After unmounting the drive and disconnecting my 935, GE 'loses' it. There are indications that GE is syncing without the device connected. On closing GE a message appears stating that issues will occur if GE is closed (sorry can't remember the exact message at the moment). Next time GE is started, 935 is not there. No problems adding the device again though. Although GE is now suggesting that my 935 is on 4.10, when it actually has 5.10.
I have a somewhat similar issue which I avoid by limiting the number of times I connect my VA to Express. When I connect, Windows 10 tells me there is a problem with my (VA) drive and prompts me to fix it. If I do try to fix it, I get a BSOD. After I reboot, all my devices that were in Express have disappeared and need to be set up again. This has happened at least 50% of the time I tried to use Express. I get a similar prompt with my Nuvi but since I only connect it to my computer every 3 months or so for map updates, it's not as big a problem.
The BSOD shows an error message that it was caused by fastfat.sys - a Windows system file. I contacted support about it. Garmin says it's a windows problem but I only get this with my Garmin products. My feeling is that it's the Garmin driver that is either corrupted or out-of-date that crashed fastfat.sys. I can connect anything else and I don't have the same problem.
