So does your username contain a diacritic or do you have a non-English OS? If so...
From sticky thread
Originally Posted by tk102
KSE closes immediately launching.
- You have logged in using a username with an accent mark, an umlaut, or other diacritic. This is a known bug associated with PerlApp.
- You have a non-English OS
- Log in using a username without a diacritic.
- Try using KSEa, Kotor Savegame Editor Alternate, which is compiled with an earlier version of Perl without unicode implementations. This available at http://www.starwarsknights.com/tools.php