Can't ping print server!

OK, having a strange problem with a client's setup:

Have an HP OfficeJet 6100 set up (with built in network print server),
and it's working fine from 2 wired and 1 wireless computer. The other
wireless laptop can not reach the printer. Pings are unsuccesful.

However, this laptop CAN ping the router and all the other computers on
the network (all of which can ping the print server AND the affected
machine). Gateway & subnet are all identical on everything. I've checked
the HOSTS file. No spyware. Windows firewall turned off, and no 3rd
party firewall installed.

Does anyone have any clue what could be causing this? Web browsing and
every other network related function seem to be working perfectly from
the afflicted laptop as well, the only thing that doesn't work is
pinging the print server. I have looked for a setting where perhaps the
printer is Ignoring the laptop, but can't find anything.

Any help?

Thanks,

Ryan