Dakota M. Lesmercy

Hey! I've had this problem ever since the 1.4.5 minecraft forge got released for the mac version. Everytime I log into a world, when using forge, and open my inv/chest/menu of any kind, i get this error: Every time it happens, and it takes me a few times of trying to open the world to make the error go away. I just re-installed minecraft again on my computer, and installed the Forge on a blank minecraft.jar, and yet it still happens. Its getting really frustrating and I don't know what to do at all...