Error in unzip

Trying to import Accounts and Contacts into Microsoft CRM 2011 from a zip file we received the error:
“Error in unzip
An error occurred while the uploaded .zip file was being extracted. Try to upload the file again. If the problem persists, contact your system administrator.”

We spent a lot of time trying to figure out what was wrong with our files. Turns out it was much simpler. The MSCRMUnzip service had stopped. Restarted it and all was well.