User names blank in task mgr - Win2k8 R2

Up until about 2 weeks ago, I could see which processes were running under which user account on my W2K8 R2 terminal servers. I can still see all processes running, but only my id and system IDs show up in the user name field. All other user names are blank Is there a gpo setting that I can verify? All of my servers changed at the same time.

I've seen posts about similar problems in Windows 7, and the solution was to turn on terminal services. Of course, the remote desktop service is on in the servers.

Thanks.