From the web, should apply to SeaMonkey as well as it is all the same back end.

Simon G

When trying to print in Firefox, you get the following error:

Printing failed when starting the document

However, when you use other applications, it prints just fine.

To try to solve this issue, try the following steps:

1. Type about:config in the address bar.

2. Locate the entry for print.print_printer.

3. Right-click this entry and select Reset.

4. Close all Firefox windows, then reopen it. Hopefully you are able to print OK now.