As we were not able to understand why Windows 7, suddenly, became unable to address the US Robotics print server on the Intranet, I purchased an external Print Server, having a direct addressing IP, and solved the problem. May be one day I will discover why ..
For years I have used an home network printer, connected to an US Robotics Router (USB input), from any of my home computers ( XP, Win7 32, Win7 64). Never a problem. From two days, suddenly, my Desktop Dell Optiplex 980, running Windows 7 64B, is unable to use the printer. I have done every known attempt to solve and read everything I found googling around. Reinstalling the printer, canceling any Firewall and AntiVirus. I have even moved the printer to local USB, with direct connection, and I printed without problems. Verified the tcp address and port data on the router. Of course the other computers continue to print regularly on the printer when connected to the router. All the network IP are fixed and the network works without any problem with many other items ( CAMs, iphone, AppleTV, ipod etc, AccessPoint - for the WiFi part of the network- and Extender) I did many other tests I am not going here to list, Always without any result. Formally the printer seems to be ok but I am unable to get even a test page from that computer. For your knowledge I have not done any conscious action or modification that I could presume to be the cause of that failure.  I need to solve this problem, therefore pls any kind of idea is very well accepted .. even crazy one ! Thanks a lot Manlio
Optiplex 980 win 7 64 Network Printer