I reinstalled each of the Visual C++ as per your thread and there are no more error messages. However, I can still unable to invoke the GSX window in FSX, no matter clicking the Ctrl-F12, Shift-F12, Ctrl-Shift-F12, or via the Addon Manager menu. I tried enable and disable the GSX menu. I can see the airport cache successful message displayed in both cases, but still there is no GSX window pop up.
I have thus un-installed the GSX together with the addon manager again. Then re-install the GSX and reboot my PC, switch off the Anti-virus, but the GSX window still cannot come out, even in default airports like RJAA, ZSSS, with default FSX plane.