the reason the screen turns white when trying to load a skin is because FP cant find the skin, nothing to load so thus its all white. You dont have to reinstall FP to fix this.
Just edit frodoplayer.ini and change which skin is loaded and resave the file.
As far as the skin thats not loaded, check that the skin isnt nested in another folder, ie;
My path to this skin is as follows
in the 800x480 dir you should see a PICS folder and 9 .ini files
If the path was like this
the above would give a white screen in FP