Why does my computer become unresponsive whenever a game goes into fullscreen mode?

My computer becomes unresponsive whenever I try to run a game in fullscreen mode. For example, Pirates of the Caribbean Online, Terraria, and others as well. It goes to a black screen and freezes there, and I can't do anything. I have to manually turn off my computer and start it back up again. I have a Windows XP Service Pack 3 Media Center Edition computer. I also have Trend Micro Internet Security, which is a virus protector. If any of this information helps, what could be causing this to happen?