Basically, you used the same method name in a derived class as is used in the base class, and that accidently overrides a function that just happens to have the same name but is used for a different purpose, takes different parameters, etc.

The first thing that comes to mind is to make sure all members are documented or follow a naming convention for "internal use" items. But, you can still hit that problem with an internal-use function! All methods that are called using the virtual dispatch mechanism, even those that are private, must be documented so a writer of a derived class is aware of them and will not re-use those names.

—John