Icon Window will not allow computer to close down

We are using Windows 2000 Server. After installing Trend Micro Client/Server Internet Security program, we started having a problem. The server will lockup, and will not follow commands from the mouse or keyboard. When we finally shut down the server (it takes several attempts) the last thing that closes is a pop-up window that says “Icon Window is now closing.” This is causing us to restart our servers through-out the day to maintain contact via PC Anywhere.