Not sure if this is applicable but you never know.
I had problems installing a HP8500A as wireless network printer on 2 of my PC's (XP and Vista). The printer could not be found with the HP setup tools. After some investigation this appeared a problem with the Comodo firewall. I found several topics on that on the net but no actual solution.
What worked for me was unchecking the 'Block Fragmented IP Datagrams'.