net use command

I am having a problem with a network printer. A software package that is loaded on a Windows 2000 machine requires the network printer to be set up as a local printer, and to net use lpt1 to the network share. The statment that I am using is: net use lpt1 \\server\printer_q /persistent:yes. The printer will work for a day or so, and then quit. When I type in the net use statement, the lpt port does not show up. I then have to redo the net use command. Anyone know what I’m doing wrong?