Error message when trying to print return labels

This happens often and most of the time if I close down SR and reopen a return label will print.
But today it just happened over and over when trying to print up a PDF return label.
I get a pop up box with this type of error message.


Unable to print label: Couldn't delete "c:\users\public\documents\z-firm llc\shiprush\labels\9401910200864325597014.pdf" (32). Reprint the label from shipping history when the problem is fixed.

Any idea what this means or how to fix?

Thanks