My 800 seems to go death as well, but I'm not sure what channels I loose. I've found two things that typically cause it.
1. Leaving it plugged into my car for power when I shut the car off (probably the same as unplugging it from the wall). Shutting off the scanner first and unplugging the radio seems to fix it.
2. Trying to add CB frequencies to the scanner (from within the GRE software)
In both cases, it looks like I can still receive conventional channels, but I loose the digital trunked channels. It's really frustrating because there's no way to tell if it's just quiet or if your radios gone deaf.
The only thing I've found to fix it is to select the "Update from Lib", which typically helps. Does this sound like the issue you've been having at all? I think I'm gonna call/email GRE next week.