I know this is an old post, but I wanted to add two solutions for people doing searches:
Both of the following services must be started, with the Startup Type set to "Automatic":
* "Terminal Services"
* "Workstation"
Disabling either of these, or setting the Startup Type to Manual, can prevent the User Name data from appearing in Task Manager.
http://www.winxptuto...tmuserblank.htm
------------------------------
Walkthrough:
1a) Goto Start, Run, type Services.msc
Make sure that "Terminal Services" is started!
Make sure that the Startup Type is AUTOMATIC!
1b) In XP SP2: Goto Start, Run, type msconfig
click on the Services tab at the top
Make sure that "Terminal Services is checked
After either of these steps, reboot your PC to see if that fixed it
2) Ensure that the "Workstation" service is also started and selected in both of the above locations
Again, in Services.msc, the startup type MUST be "Automatic"
--------------------------------
Hope this is useful for anyone experiencing this problem.
/SilentAshes