Event ID: 3012 Source: Rdr

I have a major problem at one of our sites: when printing from our accounts application, it works fine and then for some reason it loses the connection to the printer? The above events are recorded in the System Log with the message:
“An unexpectednetwork error has occured on the virtual circuit to {computer name}.”

The application uses windows printers, but when we can’t print from the application, we are stll able to print from other programs???

Any ideas would be appreciated.