It will help us a great deal to know what version of Finale and operating system you ran on your old computer and what OS you are running on the new one.

Can you also tell us what the extension on your older files is (the three or four letters after the dot in the filename)?

How are you transferring the files from your old computer to the new one?

Old computer: OS X, new computer, latest version of windows.  The files are .musx files.  Transferred them with a flash drive.

How are you trying to open them? By double-clicking the file or by using the File > Open option from within Finale.

You might also try sending one of the files that will not open to MakeMusic via the "Submit a request" link at the top of the page to make sure no corruption has crept in during the transfer.

Oh weird, but using file > open, some of them just open, and some of them say "hey you made this with Finale 2014 so do you want the program to 'translate' it?" and if I click OK it just does. 

Wouldn't have expected that to make a difference.  Thanks!

So, this is weird and frustrating.  Some of the files in that folder I can open on my windows laptop, and some still give me "invalid file type" even though it's .musx.

I am unable to playback and I don't know why. Suddenly it stopped. I had not experienced this problem before. Can anyone help please?

Father Arshen,

PLEASE read the house rules. 

https://makemusic.zendesk.com/hc/en-us/community/posts/215729367-General-Discussion-House-Rules

That will help us diagnose your problem. In the meantime, the first thing to try is always to restart the computer.