If you run an application with /REALTIME priority, it may appear to hang Windows NT, if the application is not designed to be run in real time priority.
Power Users and Administrators are granted the right to Increase Scheduling Priorities by default, and you may have granted this Advanced User Right to others.
To remove the right, use the local account User Manager or usrmgr \\Computername. Then Policies / User Rights / Show Advanced User Rights / Increase Scheduling Priority and remove the user or group from the Grant To box. You can also remove the SeIncreaseBasePriorityPrivilege in batch.
If you want to demonstrate the problem on a uni-processor:
1. Open a CMD prompt.
2. START /REALTIME EDIT.COM
3. Press the Esc key.
4. Wait 10 seconds to allow any disk activity to complete.
5. Select the File menu and press New.
6. Your keyboard and mouse may stop responding, requiring a hardware reset or power cycling the computer.