Apps become minimized into a title bar o

Our desktops are currently installed with NT4 SP6. Our users are given standard office apps (IE, Office, Acrobat, Notes, etc)
We have encountered a problem w/ some users in which minimizing an application minimizes it into a small title bar floating on top of the desktop… it does not go to the task bar. The close and min/maximize buttons become grayed out and the application often needs to be killed and restarted in order to function again. What can be causing this? Our most recent corporate roll-out was SP6 to the desktops. However, only a small number of machines are exhibiting this behaviour. Is this hardware related?

Alan Lau
Capital Group Research, Inc.