You should remove C:\usr\lib\unixroot\usr\lib\firefox-45.9.0 from your LIBPATH and run C:\usr\lib\unixroot\usr\lib\firefox-45.9.0\firefox.exe Any program objects should also use this as the working directory.
Finally I have been able to start the seamonkey.
I have removed everything from the libpath. Both in config.sys and in usr \ lib ..
In firefox45.9 I started it from any folder. Unzip and execute, perfect.
But the seamonkey failed again and again, with the path without the path and in usr \ lib. Delete everything in d:\home\seamonkey, copy the profiles from firefox to seamonquey and everything perfect, now I execute it from any folder.
Do not copy the thunderbird, because it's not my idea to use the seamonkey.
The videos look just as bad.
saludos
regards