Not sure what to tell you, haven't heard of this behavior before.
However, FileMaker 10 is beyond end of life for support, and is not listed as compatible with Windows 10.
You may want to rollback any other updates that computer has had after originally having filemaker pro working. EG java updates or something else. Maybe using an uninstall scrubber application like Revo to remove all traces of filemaker before reinstalling.
In the end though, for the best compatibility, time to convert to something that's not 8 years old.
Thank you. I have considered updating but because this is a small office it's not something I am looking forward to. I'll have to research it to find the best plan for updating.
I'm convinced that some sort of update in windows 10 did this. I did uninstall all of the recent updates from microsoft. I'll look for other programs that might have affected this as well.
It's been my experience with FMP 10 and WIndows 7, that after a certain number of months of usage, the entire system gradually loses it's ability to correctly manage windows in terms of opening and positioning them and FileMaker starts crashing. This includes dialogs and tabs in a web browser.
The cure was always to uninstall and reinstall FileMaker.