Despite my not consenting to an upgrade, Windows 10 appeared on my computer overnight about a week ago. Formerly, I used Windows 8 and was happy with that program. Windows 10 was one problem after the next, including the disappearing cursor that took me forever to fix.

My bigger problem is a movie I have that I made on Windows 8, MM2.6.  It worked fine there. When I opened it in 2.6 in Windows 10, I couldn't render the file-kept getting a message "cannot save."  Finally fed up, I recovered Windows 8. Although I can almost fully load my movie again there in MM2.6, it won't open. Instead I get a message that says "unspecified error."

I'm now stuck between both programs and unable to open or render my program in either. It appears to me that after I transferred my movie to Windows 10 and saved it there (as well as another short video file that I made with MM2.6), something in Windows 10 changed both of those files that no longer allows me to open it in Windows 8.  I can still open all my other video files made with MM2.6 in Windows 8, just not these 2.

And someone else with Windows 8, MM 2.6, that I sent my video file to, also cannot open it in Windows 8.

Something changed with these 2 files with Windows 10 and I need to change it back so I can open it. Compatibility scans show nothing.

I also thought about setting a restore point before the Windows 10 upgrade, but Windows 8.1 doesn't allow the administrator privileges to manually do so. It only allows a preset restore point of a few days ago which is not enough as the Windows 10 upgrade occurred about a week ago.

Such a mess.  Please help.