I ran a program that I had made a while back, and it gives me a weird error message when it ends. I have it set up to send me to the graph screen at the end of the program, but when I close out of the graph screen, it just gives this weird error message that just says "Error: ?" with only an option for quit. When I hit the quit button, it just reloads the error message screen. The calculator won't even let me turn it off. The only way I can get out of this is to unplug the calculator from my computer and plug it back in. Does anybody know what is happening and how to fix it? If it makes any difference, I am running OS 4.0 with Doors CSE 8.2 installed.

This is because the Doors CSE hooks are interfering with your prpgram. You can deselect the option to use hybrid libraries in the settings menu and that should fix it.

More specifically, the program has hit an unusual error that the OS is not communicating well to Doors CSE. If you temporarily disable HomeRun from the Doors CSE settings menu and then run the program from the home screen, you should get a more descriptive error (and on what line it's occurring).