Why is it not possible to completely uninstall GSX including the register items and do a clean install with the activation serialnumbers I still have?. Could that possibly make GSX working again?
First, why you think "it's not possible" to completely uninstall GSX, and why you think this might be caused by a registry entry ?
If the problem was that you needed a GSX reinstall or a registry entry, I would have told you how to reinstall it and/or how to clean a registry entry but, the problem is, nothing of your problem has anything to do with GSX, because according to your log, GSX IS starting, but the simulator has disconnected from it.
Fact other add-ons are working doesn't mean anything, there are several Simconnect versions and they can be installed all at the same time, and each add-on might use a different one so, for example, an add-on that use the FSX version CAN connect to P3D 4, if that one is working and yes, it's possible that a problem between the two would prevent another add-on that use a different version to work correctly, because the add-on using the outdated ( but working ) version, might have stuck the sim in that version.
GSX in P3D 4 uses the native P3D4 version of Simconnect so, if you have a problem with that one, but not with other versions, add-on using the FSX version will still work, but not the ones using the native 4.x version, like GSX
First thing to try, is to disable EVERY add-on except GSX, which for proper add-on that use the add-on.xml method like GSX should be fairly simple: disable them in the OPTIONS->ADD-ONS menu. However, legacy add-ons might still use the DLL/EXE.XML files, so they can only be disabled by manually removing their entries from those files, or uninstalling them.
If you are able to run GSX with all the other add-ons disabled, then it's SURE your problem was caused by an add-on using an outdated Simconnect version that caused a conflict with the proper version used by GSX, which would otherwise work.
If, instead, you still get that problem with all the add-ons disabled, then you might really have a problem with the P3D native Simconnect, which is usually fixed by Uninstalling/Reinstalling the simulator that, opposite of what many think, DOES NOT require to reinstall add-on.
Of course, all the usual suggestions are stil valid:
- Configure the antivirus to exclude the whole Addon Manager folder
- Run the FSDT live Update after the antivirus has been proper configuired.
- Sometimes a Windows restart might help, in order to complete an update of the VC++ runtimes required by Simconnect, P3D and GSX.