I'm not sure, because your computer screen is not directly in front of me, but so many times the error is in syntax:
Autocad does not always like single backslashes. your plotter should read something like:
\\ntserver\HP Designjet 2000CP
If that doesn't help, perhaps we could work together to figure it out. I would need a copy of the printer installation disk to create a phantom printer on my machine. Then we could compare error messages until we solved it. If you need to go this route send an email to bfranzus@syclone.net