xp – dos app – lose network printer

I have a DOS app which requires the port to be specified as LPT1 etc. The printer is an HP4050, not a print server, just a shared printer on an XP workstation. Some machines are fine with just setting up a network printer with LPT1, others I haveto use the net use LPT1 \\sharename etc \persistent:yes. When using the net use, I randomly lose the connection to the DOS app. Windows knows its there, but my app does not print. It thinks the printer is there as there is no error, but nothing prints. Anyone got any thoughts on why the DOS print jobs don’t print?

I am getting desperate..Microsoft offers no help. Yes..no comments about the DOS app, but it is app specific and no Windows based replacement yet.

Thanks,
Laurie