This has been a fairly common problem with no clear answer from Gerber. Some of the possible causes are:
1. Incorrectly configured Rainbow Sentinel Driver
2. Incorrectly configured LPT port
3. Bad LPT port or printer cable
4. Software bug - what version are you running?
5. Glitch in the job file itself.
We used to have this problem and it was related to the fact that we were running three chairs of Graphix Advantage (at the time) with the dongles setup to allow common items like fonts to work on all systems. The Edge was connected and shared on an NT server.
A GSP tech rep I talked to about it told me the job was going out to download the next packet of data and finding the wrong dongle and to stop sharing the Edge as I was doing. Instead, he suggested that I connect it to one workstation and then map it as a device to the other workstations. We did this and have never had the problem since.
A GSP software engineer has since told me that this explanation could not be correct since the Edge does not check for a legal dongle once the job has commenced printing.
Whatever the reason, changing the way we had it connected eliminated the problem. I suspect that it may have been related to the server using Windows NT 4.0 as its operating system.
Sometimes something can be wrong in the file itself. Try copying and pasting the job into a new window, close the old and save the new window version under a different name. Then run it from that file. Using a different name will also help in that the saved .PRM file won't be used for the new print run.
Hope this helps. You might want to post the same question at
www.4edgetalk.com There are a couple of Gerber technical people there that will help you find your answer as well as a lot of Edge users.