GSX won't install properly.

[lyokoBSTN]

Okay, so I'v had GSX now for a few months, and it has been working perfectly well the entire time. But suddenly a few days ago, it stopped working. Now, this I can only assume had something to do with an installation of the QualityWings 757, as the problem only started at that point.
I have removed the QW757, uninstalled GSX, and then following the instructions I have seen plastered on almost every single issue regarding the GSX install, I turned off my antivirus, excluded the Couatl.exe and Bglmanx.dll files from realtime scanning.
Now the install goes through properly and completes (But only when I manually select the path to the FSX-SE folder. The auto selection just comes up with an error every time)
I start up FSX, load up at an airport, and nothing happens.
The Couatl menu, GSX menu, and the SODE menu in the Add-on drop down don't show up at all.
I'm totally stumped at this point as to what could be the problem.
Any help would be much appreciated.

Oh and a side note, as I'v also seen it said many times. I doubt my anti-virus is faulty. It's a top end one, and it has never been an issue ever with programs, and as said before, GSX was working for a few months without issue until this fault.

Thankyou for your time.

[virtuali]

Now the install goes through properly and completes (But only when I manually select the path to the FSX-SE folder. The auto selection just comes up with an error every time)

This clearly indicates your FSX:SE registry is messed up. Most likely, you installed another addon that doesn't support it properly, so it has screwed your registry assuming it was FSX.

See this reply here, which explains how the registry keys are supposed to be when the sim is installed properly:

http://www.fsdreamteam.com/forum/index.php/topic,14166.msg104727.html#msg104727

[lyokoBSTN]

Many thanks. Some playing around there with what you explained in those topics managed to work (Eventually)
GSX is now back working properly again.

Many thanks for the help.