Not sure if $taboo was getting sanitized or not. Possibly an SQL injection vulnerability that allows maliciously crafted group names to inject SQL at a later date when the group CP is loaded. Unconfirmed, theoretical fix.
Beginning with version 2.0.5 the language packs are no
longer included with the core distribution.
Language packs can be downloaded from the TinyMCE website:
http://tinymce.moxiecode.com/download.php
The language pack codes are based on ISO-639-1:
http://www.loc.gov/standards/iso639-2/englangn.html
Plrease try using entities if possible. Like å etc for non a-z characters.