Until to day I used TCC / TCMD version 11, but under Windows 10, HELP often crasshes. Ok, may be time to buy a newer version 18. (64 bits) So I got the evaluation version. Any attempt to open a BTM from Windows Explorer, now result in a TCC windows opens, displays an error message to short to read it, and closes. During installation, I did not tell the installer to associate BTM files (or any other file) with TCC as version 18 should use the associations of version 11, including my right mouse options like Edit with my editor, Debug, Print etc. Just "Open" does immediately close in version 18 :-( Starting the BTM from the command line works Any idea what may be wrong?