I had a major problem with my computer - too long a story - Needless to say a computer shop technician had to reinstall my operating system, Windows 7, install Microsoft Office 2016. Of course there were several other programs that had to be reinstalled. So recently I downloaded the latest version of Chimera and have been able to work with PDB files and do all the things that I am used to doing. However, I always save the sessions that I have worked on. They are saved to the desktop C:\users\user\desktop The session files are saved to the desktop. Now comes the problem. When I double click on the file I want [cid:image002.png@01D2A987.C67BFFE0] I get the following message [cid:image001.png@01D2A986.AAC7D360] If I right click on the file then in the menu window click on open with Another window opens with Chimera being the recommended program. Click on OK and the same window as above comes up. This happens even with a .py file that I worked on today. I am puzzled. Ideas will be appreciated. Arthur G. Szabo