Network printing and SP2

We are running a Windows2000 server with an HP4050N
printer attached. I have set up a test machine with SP2
installed to see what affect this will have. Thus far it
has been unable to printer properly to the HP4050N via the
network. Standard text is okay but anything, including the
test page, that provides any merged document will not
print. I also cannot install any other drivers, that
option is grayed out. I have disabled the firewall, also
no change. Any suggestions? Merged documents are a
requirement when invoicing. At this point I do not plan
on installing SP2 on any active machines. Thanks