How to remap F5 key?

For some reason F5 is launching the calculator app on my work machine... which is kinda strange, since this doesn't occur on my home machine (both running Tiger).

F5 isn't listed in System Preferences>Keyboard>Keyboard Shortcuts, nor does the calculator have any settings that can be changed.

I have to use the F5 key with the telnet app I'm using, so I'm hoping someone can tell me how to stop the calculator from launching...

Never mind.

I figured it out... some piece of shareware installed this "feature" into startup items. I turned it off, everything's cool now...