AutoCAD 2006 will not hold plotter settings

Hello.. Sorry if this makes little or no sense but I've very little experience with autocad.  Read that as none!!  A user here has recently had Autocad 2006 installed on her machine.  She has a HP designjet 1050C installed on hermachine (there are two in our company in two offices).  If she goes to plot to the one on the same subnet as her, closest to her location, she is unable to change its settings to oversize iso a1 (landscape).  I've checked the printer settings, but every time I change the custom properties of the printer from within acad, it reverts back - closest I can get it to is oversize iso a1 portrait.  It just will not go to landscape.  I added the same model printer in a different location (different subnet) to her machine and this works fine and holds the settings with  no difficulty.  What am I missing here??  Others around her are plotting to that machine with no problems.  Help me!  Sorry if I'm missing something glaringly obvious, but I don't have an autocad background!