So what could possibly be the problem if I only have the problem when GSX is installed?
Why you keep repeating this thing about GSX being the only addon installed ? A LOT of things in your system can cause this, which might not have anything to do with the simulator, most likely system libraries missing/corrupted/conflicting, and since their effect it's not the same, depending on the version of the sim, I've asked about the precise, exact, version of the sim.
So, please, do as requested. Then, after checking that, we'll check other things, and we'll find out what other software (again, NOT necessarily flightsim-related), which affecting GSX.
And I have seen posts where the issue was been discussed, I thought the developer would be able to be a bit more reasonable and try to find out if just possibly there might be an issue that is been overlooked.
And all of them, at their conclusion, eventually proven it was something else, and GSX was always the victim of some other problem, not the cause.