Cannot connect to a network printer.

At one point I was able to print to a printer on our network and one day it stopped. When I troubleshoot it says the printer cannot be contacted over the network. I have the correct Port Name and the IP Address. I’ve deleted the port, and re-configured the port but with no success. I also have always had intermittent problems connecting my pc to our network. I have a new pc now with Windows 7 but am still having the same problem (all the other pc’s have XP – but we had the same problem with the intermittent connection to the network when I had XP – I was always able to print to the printer when I had XP). I am at a loss as to how to solve the connection issues we are having. Any suggestions would be greatly appreciated.