File name changes will not save - application freezes since update

I downloaded the new software update today and now the application will not function properly. I tried to uninstall it and download an older version of the app with the same results. Before the update, I had no problems, but now when I try to edit and rename my files, the app freezes on "Writing tag data" and does not save even when left to save for an hour. Please help! I wish I had not downloaded the update because it was working just fine and now it's practically useless!

As apprently the update is not the culprit, you have look for local causes.
Make sure that no other application accesses the files that you currently treat with MP3tag.
Also check the files for consistency, see the Howtos for suggested tools.

I used the application earlier today before updating it, and it worked efficiently as it always does. None of my other applications are accessing the files I'm treating with mp3tag.

Yes, of course.
But as you say:

so as MP3tag worked before and now it does not even if you revert to the previous version, you have to check what else might have changed. It would be interesting to see what happens if you edit the files again that worked before.
And please check the files for corruption.