There are so many things that can go wrong in file sharing - and many of them produce obtuse error messages. Here are a few ideas to try:
  • Make sure you have the Client for Microsoft Networks and File and Printer Sharing for Microsoft Networks installed on your network adapter in Network Connections and they’re both checked.
  • Check the Advanced properties on TCP/IP networking to see that NetBIOS is enabled - Windows needs it to share printers.
  • Make sure all computers on the network have the same workgroup name. Stick with uppercase letters and numbers for maximum compatibility. Use the System control panel, Computer Name tab to do this.
  • Check the IP addresses of both computers to make sure they’re on the same subnet. (They should both begin with 192.168.1.x or 10.0.0.x). The first three octets should be the same on both systems)
  • Check to see that the Server service is up and running. Click Start/ Programs/ Administrative Tools/ Services.
  • Turn off any firewalls - they’re unnecessary with a router. If you want to use a firewall you’ll have to configure it to pass sharing through.
  • Make sure Wireless Privacy is disabled on the wireless router. Some wireless access points use privacy to block other wireless computers from connecting and this can prevent printer sharing.
  • One computer on every Windows network is designated the master browser. This computer is responsible for maintaining the networking connections between computers. If the wireless computer is designated the master browser that can cause problems since wireless computers can drop off the network at random times. It’s best to make sure the wireless computer can never be designated the master browser. Open the Services program again, double-click the Browser service and disable it.

Windows Networking has several useful articles on networking issues.