So it seems the bug is triggered just after the MiNT boot menu, if a key is hold down at that time.I really hope we will be able to find the cause of this bug and fix it.
Your problem is: Your computer is too fast: While your on that key, MiNT already initializes. One could add a loop: Cracin() == '\r', but then you would only be allowed to press return, and it could hang then if no return comes in.
So: If a key is pressed during MiNT-boot, that key will not go away. That's at least my theory atm. Or EmuTOS should eat everything, but the bug is in MiNT. The source can surely be found in keyboard.c -Helmut