Dear @CitizenJoe,
Well, there are a lot of variables here. 1.x file, moving from Mac to Windows, etc. But if it's crashing in when you're trying to locate the media, then I would suspect the media itself maybe. I mean, you can certainly go back to 2.0.5 if the file is a 1.x file, given that 2.0.5 will supersede the features of 1.x. But another approach would be to
1) Open the file without any media
2) Replace the media one at a time by double clicking on each item in the Media view. Save after each item until Isadora crashes. In other words, if it is in fact the media that is the problem, you'll discover by doing this step by step process.
I would also trash the preferences. You'll find them at
c:\Users\YOURNAME\AppData\Roaming\TroikaTronix
The preferences will have the version number 2.1 in it.
Best Wishes,
Mark