Grabowskis ERJ panel-- problem with PFD and MFD

After my post yesterday, I suddenly started to have a problem with the panel when I commenced re-acquainting myself with it. This is that the PFD and MFD go "black" after a few minutes of operation -- I can't get to the stage of pushback. In FS2002 , with the freeware FSUIPC , there was an option to have unlimited battery power so that you could take as much time as you wanted to start-up. But the latest freeware version does not allow this. In any case, as other electrical items do not die, I am not convinced that this is even the problem. But they do seem to stay alive if I start up engines quickly before setting up the cockpit and pushback-- so it seems that it has something to do with the power supplies.Any ideas?Thanks Barry