I found this in another forum:
The Wii console can detect unnecessary files that may be saved on the system. When this happens, these files are displayed as a question mark (or marks) in the Data Management screen of the Wii System Settings, or in the Wii Channels menu. Deleting these files will remove the question mark(s). There are no harmful effects caused by deleting them. Straight from Nintendo |
I couldn't find anything from Nintendo on that, so I don't know how accurate it is but I have seen that response before.
Edit: found the source http://blogs.ign.com/bbb7002004








