aubite,
Repeat the plist removal which I specified in my first post, then open System Preferences...>Lanuguage & Text>Formats>Region: and set/re-set the appropriate region.
You can delete any/all of the plist files which were moved to your Desktop. The plist file could be trashed immediately, but it may not have been the problem, and dragging it to the Desktop allows replacement if that is the case.
;~)