This may be related to the SDL library / Wii libraries supplied with the nightly build.
If this is still occurring with the v1.6.0 release, then can you try earlier releases i.e. v1.5.0, v1.4.0, v1.3.0, v1.2.1 etc back to 0.12.0 if possible. Try to find when this problem was introduced or whether this has always been this way...
(but when it comes to old versions: i was starting with the beginning of the scummvm port to use it on wii and i cant remember that it was any different)
Any Idead when 1.6 comes to the wii or where i can download all the old wii versions? ^^ (maybe i am really blind atm and cant seee the links on the homepage -.- )
As I said "Please try with the v1.6.0 Wii release WHEN it becomes available on the download page:".
The Wii porter is very busy IRL (and probably due to issues with libogc and toolchain) hasn't provided a v1.6.0 build yet. If/When this is provided, it will be added to the download page.
I am basically asking you to do a "Gross" bisection, to see if this was always like this and approximately when it was introduced...
The nightly builds (stable) are effectively the same as v1.6.0, the development night builds (master) are v1.7.0git and older release packages can be downloaded from here: http://sourceforge.net/projects/scummvm/files/scummvm/