This issue occurs on NPS desktop computers when there is no connection to the network.
If you cannot login to your computer and are getting a tree or server error, you can usually solve the issue right away by checking the ethernet or network cable.
1. Check that there is an Ethernet cable connected to the back of the computer. These cables are usually Blue or Yellow, but come in any variation.
2. Follow the Ethernet cable to check that it is connected to either A. a wall port or B. a desk phone. In classrooms you will most likely have configuration A and in Offices you will see B.
If there is no clear issue when checking steps 1 and 2, submit a ticket and someone from IT will troubleshoot further.