I've been plagued by this issue for the two months I've owned my G5. I've not been able to determine any particular circumstance that may have caused this error. Periodically, I'll also receive a Charging Error #11 after the initial error message disappears even if the pager has not been charged recently. I even received this error on powering up right after a battery pull. Sometimes, the pager will spontaneously reboot after receiving this error without my intervention, and at other times the message will disappear and the pager resumes normal operation. The error seems to occur in batches. Yet, there are times when I can go through several power-up's without any error. So far, the error has only occurred when turning the pager on.
I've tried some of the posted "solutions" with no effect (voice storage on/off, buffer on/off, unchecking various "paging functions"). The G5 is always charged using the supplied cable and charger. The reference to "system" in the message has me wondering if there's an issue with the P25 systems I've programmed. To address that possibility, I loaded programming consisting of only some VHF frequencies, and experienced the same problem. I tried powering up the pager while on an unprogrammed knob position and still got the error.
Oddly enough, I can predict when the error will occur. As the pager starts up, the longer it takes to adjust the screen brightness to my programmed setting (manual 4), the better the chance of the error occurring. Alternately, once the brightness reduces to my preset level, the error never occurs. Coincidentally, and also since delivery, I get a noticeable flickering of the screen brightness if using a level higher than 4.
I'm just praying that the upcoming firmware update will kill this bug for good!