If you have intermittent issues printing to some printers via ShadowPrint, you can try stopping the ShadowPrint Service and stopping and restarting the Windows Print Spooler service. If that doesn't work, you may need to delete files from the Print Spooler folder. To delete the files from the spooler, follow these steps.
1. Go to Windows Services Applet
2. Stop ShadowPrint Service
3. Stop the Print Spooler service.
4. In Windows Explorer, browse to C:\Windows\System32\Spool\Printers.
5. Do CTRL+A to select all files, then pick delete.
6. Start the Print Spooler and ShadowPrint services.
You can watch the folder; you should see documents moving through the folder as they spool and print. Check with the end user to verify the printed documents.