First try to open the original file to see if there is something wrong. If there is, it will be linked in with the error.
Then see if it links into a blank file. It might be your working blend file that is corrupted causing the issue.
If it works in a blank file, the issue is with your animation file. So try appending in all the parts of your broken file to a fresh one.
To me it looks like the end bones are scaled down to 0 or something. So try making all the layers visible and all the bones visible, and press Alt S (with all bones selected)
Hopefully, one of those ideas will fix it.
