Following these steps will typically resolve any login issues you might experience:
1.) Verify that you are logged into your nurse.com account.
2.) Visit https://www.nurse.com/signup.html?UpdAccountInfo=1
3.) Don't modify your info. Simply confirm your current password at the bottom and click the "Save >>" button.
Then go back to http://forums.nurse.com and you should be logged in. If you're still not logged in, log out and close and reopen your web browser and then login once again. Also try to Log out / Log in.