Lately, I've been encountering severe trouble trying to get the radio to "leave" a fairly active system. Today, there seemed to be nothing I could do to get my G4 to switch off of the Philly Pa system even though I was a couple of counties west of Philly. I don't think it was receiving anything - in fact, it didn't record any voice calls for nearly two hours during my trip (recordings jumped from Philly PA directly to Carroll County MD - well over 100 miles of nothing).
I tried everything short of removing the battery (I was driving) -- mashing on the buttons, removing the antenna for several minutes, powering off and back on, removing external power, combinations of all of these... no matter what I did, the radio just kept showing supposed activity for talkgroups in Philly PA (with no voice). It was almost as if the screen updates had buffered in the radio and were catching up for the next several hours even though I changed off that systems entirely (or at least tried to).
Then, for a while, the middle of the screen (zone, system, talkgroup site info, etc.) remained completely blank. The top and bottom lines showed the time and other normal things but the main part of the display remained totally blank/black. Later, I noticed occasionally the display would momentarily flash some zone/system information but it wasn't receiving anything.
Eventually, it started receiving voice calls for the area I was in but the main part of the display continued to be blank. Finally, perhaps and hour after that, it started acting close to normal again.
All-in-all a fairly disappointing day with the G4. Obviously, I've pushed the thing well over it's limits.... glad I avoided I-95 on the drive home -- the combination of the G4 acting the way it was coupled with the traffic on I-95 would have resulted in someone getting hurt....