Error (111) : This document could not be saved. There was a problem reading this document.

I was recently marking up a document on a different computer using normal Adobe. I saved the file to a thumb drive and opened on a different computer in Adobe Reader. The file opened fine and I made some comments/mark ups. I tried to save the file after about 2 hours and I got an error message "This document could not be saved. There was a problem reading this document. (111)". Anyway to fix this without losing my work? Thanks.