This tech support !!! I'm amazed the "solution" of the question !? 
I'm not sure what you are trying to imply, putting quotes about the solution. Those are the solution that have proven to work for most of user that had a similar issue. Fact you confirmed you have some errors related to "Side-by-side" CLEARLY indicates you have a problem in some of the Side-by-side libraries that are required by FSX to work properly with 3rd party addons which are:
- Simconnect SP2/Xpack, which are required by GSX and every other 3rd party addon not compiled with obsolete versions.
AND
- the VC++ 2005 SP1 runtime libraries, which are required by the Simconnect library itself.
Those are the ONLY "Side-by-side" libraries needed so, according to your own report, if you have such error message, it's sure than your problem is on either one of these, or both.
They can USUALLY be solved in the USEFUL thread I linked. But sometimes, they aren't, and it might be easier to just reinstall Windows than trying to sort it out manually.
That's the main issue with Windows Side-by-Side libraries that, although they are supposed to fix a lot of problems with different (incompatible) versions of the same .DLLs used by different products, they can create a whole new set of problems, when things go wrong.
And this is not really my opinion. Want to hear ANOTHER opinion ? See this, from Pete Dowson, FSUIPC author:
http://forum.avsim.net/topic/323009-simconnect-gone-mad/?p=1909995#entry1909995I'll quote here the relevant part, where he's saying exactly the SAME thing:
I've got two PCs, one running Win7 and the other XP, and both of them have broken SimConnect installations. I have not been able to find any way to repair either without reinstalling Windows. I actually broke them deliberately (!) in order to research this, but I failed miserably to find a solution other than Windows re-installation (which I'll do one day, if only to tidy up my increasingly rubbish-ridden systems).
In my opinion the side-by-Side library system is the most diabolically convoluted system ever conceived and implemented by Microsoft and when it goes wrong it is fatal.
Here he's referring to Simconnect, which is just another Windows Side-by-side library, same as the VC++ runtimes, so it's the same issue, really, just that with Simconnect it's easier, because there are only 3 versions, and only FSX use that one. The VC++ runtimes are way more, there are multiple sub-versions for every major versions, and they are used by *everything*, basically.
