FS9 APPcrash... has this happened to anyone ?

I will try to give as much details I can, in order to be clear.

Last week my PC (win xp pro) crashed, so I took the opportunity to upgrade to Win 7... totally new experience IMHO...

Anyway the setup was clean from the start... FS9, Squawkbox, registered FSUIPC3, registered PMDG 600/700/800/90, registered FSlabs driver, registered REX environment software, and FS navigator.

As far as hardware... CH yoke, Cockpitsonic driver for the MIP, Leo Bodnard BU0836X, CP_Flight MCP+dual EFIS and all radio panels, plus two TH2GO digital devices.

All straight forward, no problems during installation.

I run fs9 without any problems in the beginning, did few modifications in FSUIPC (buttons & switches), joystick assignements, also in advance options of Squawkbox, put all my usernames and passwords where it was needed and I put the FS shortcut in windows startup to be loaded after windows startup and I was ready to go.

Somewhere during modifications an APPcrash message when FS9.exe was opening:

reason: APPcrash
program: FS9.exe
module: StackHash_bf56

After that I have the option to close the program, which I do.

If I run FS9 again, most of the times this message does not show again and FS9 starts as usual....

Has anyone had such a case before ?

Thanks in advance,