This was the problem!!! Now I spent two weeks of hard testing together with the users wh reported this first and I didn't came to this idea .-( When I deliver this manifest fil togehter with the Dlls mentioned in this file, it works.
Congratulations on identifying the problem!! I still remember the days I (we) struggled on the manifest problems, until, only by chance, Abdel found out that .manifest file for QtCore.dll need to be embedded. I do not know whether or not I can embed this manifest file with lyx.exe, since it has already been embedded with QtCore.dll.manifest. Please try: mt.exe /MANIFEST /path/to/this.manifest /outputresource:lyx.exe:1 on your lyx.exe file, and mt.exe /MANIFEST /path/to/this.manifest /path/to/qtcore.dll.manifest /outputresource:lyx.exe:1 and see if you can embed two manifest files at the same time. Cheers, Bo