FSX won't start

[NW253]

First of all, I have searched the internet and especially this forum for answers.
I have tried everything.
Most of the answers I found point to the anti-virus.
This is what I did:
After having some display issues (missing terminals at FSDT sceneries when I arrive at them), I decided to reinstall them all.
I uninstalled every single one, even the FS9 versions and Flightbeam's SFO, uninstalled the Addon manager, deleted the folders manually in FSX scenery. After that I disabled my Anti-Virus (MS Security Essentials) I then installed ONE scenery, doesn't matter which one, I've tried several. As soon as it is installed, FSX won't start any longer. No error message, just quits after the splash screen.
My antivirus is definitely disabled (real-time protection off and even terminated the process and disabled my firewall. (Windows Firewall)
I am at a complete loss. I can't do anything anymore...I've spent today trying to sort this out with no success.

Has anyone of you ever had any issues like this? Or any idea what to do?
The installation of the sceneries is working fine...no errors and everything is downloading normally. I even excluded the bglmanx.dll and couatl.exe in my antivirus.

Any help would be greatly appreciated.
Thank you

[virtuali]

Don't remove anything, reinstall everything and try to install the Stand-Alone Addon Manager after everything else. Yes, do it again. Yes, we just updated it now.

[NW253]

YES, that fixed it! What did you do?

That's awesome and will probably help a lot of people.
Thank you so much...I'm definitely gonna buy GSX now. 

[virtuali]

YES, that fixed it! What did you do?

As I've said in the other post, basically nothing, other than changing something in the linker flags that might have affected those users with corrupted/missing C++ libraries.