Troubleshooting Operating System Connectivity

If you are struggling with operating system connectivity issues, consider the following:

Username/password Make sure that users are logging on to the network with the correct username/password combination.
Configuration It might be necessary to confirm that the network settings on the client computer have not changed.
Account activity You need to verify that the user has an active account on the network and that it has the correct permissions set. Log on with a known working account from the client's system, which will allow you to isolate the problem to the computer or the user account.
Physical connections You should check to see if a cable has come unplugged from the client's system.
NIC To confirm that a card is working, you might need to swap out the card with one that is known to be working.