Okay.... I think you might want to try repairing your game.
If you're using Windows XP, go to My Computer on the start menu and click on Local Disk [C:]. Then, go into Program Files and find the RPG Maker XP folder (might be called RMXP). In there, there will be two folders that have the word setup in the title, and there should be a .exe file in each of them. Run both of those and click the repair option when you're asked what you want to do.
That might work. It's fixed some weird problems I've had before.