I think a little more info may be required

If your talking about moving arround the task bar or hiding it then yes there is a way. You can have it on the top bottom letf and tight side of the screen. Then there is the option to hide it. Just right click the task bar and ther is an option in the setting for it to hide it.
EDIT: The this comp. has been locked and is in use message I don't think is simething you can hide, seems that there is some sort of error occuring. Sorry about the task bar answer. It may be possible that you have a virus or that someone has hacked your system. If you restart does the message come back? Are you on dial up? If so nevermind that

If its cable or dsl (with an external modem) unplug it and shut down and hook everything back up and restart. Were you running any programs when this happend, like maybe NetMeeting? Need more info
