Can't edit Games menu
 

For some reason Alacarte does not seem to be able to edit the Games menu on my Debian Lenny machine. I want to remove the icons for several games I don't use, and add icons for a few others. However, new items do not appear (in Alacarte or the menu), and whenever I uncheck one of the existing icons in Alacarte, the checkmark reappears like magic a few seconds later. I'm mystified. Any ideas?

Edit: I forgot to mention that it doesn't work if I run alacarte as root, either. It behaves the same way under root as it does as a standard user.