This seems to be a "feature" of the original hotfix. Without the fix using G etc the chatbox works fine, add the hotfix and what you describe happens. In another thread buried somewhere Ryan did acknowledge that they were trying to fix something else and this was a knock on affect, he said 'fix pending' so presumably this will be sorted in the next hotfix.

Just tested it and it's sorted in the latest hotfix

Thanks guys,hope the PMDG reads here and with the next hot-fix corrects this error! Maybe it is also likely that SP1?Let's see, maybe I'll reinstall the NGX also easy again! ?

I think all you need to do is install the next hotfix, not reinstall the entire aircraft.

Disable FSInn weather and use ASE, REX or even the default FSX real world weather.

The temperature inversion problem flying under FSInn's 'server' weather takes place above FL240. My online group has been investigating a solution to this problem for a while. At the moment we use FSX's RW 15 minute updated weather. Usually very similar to VATSIM server weather. When I fly on VATSIM I use RW 15 weather and don't get any issues apart from occasionally having to tweak the QNH. GL.