Some bugs appears when an extra Language Package is installed. People reported special characters not showing up, strange characters on the Sharing Pref Pane, and the more nasty; Finder Pref Pane crashing. I have made a fix for the last one. It must be applied right after you installed your lenguage pack.
http://www.mediafire.com/?j1uxngmjmyz
My recommendation is to either use the default english or, if your language is a must, try another distro. I belive (I might be wrong) the Language Packs everybody are using (from 10.5.4 retail disks or older) are for some reason not fully compatible.
