This confirms my assumption from my first post. If you want to open .2da files to edit them, you will need to download and install KotOR Tool. If you are already aware of that, my apologies.
As Star Admiral points out, my second assumption must also be correct. You are having a mod conflict, and if you tell us which mods you have installed, we may be able to tell you which ones are in conflict.
Also, you might have better luck posting in Inyri's TUCE thread about Recruitable Kay. That thread is specifically about that mod, and the developer may be more willing to help you resolve conflicts if addressed in the proper arena.
Otherwise, tell us what else you have installed... we will figure it out :)iny doesn't post here anymore. you can ask on her site though,
http://inyri.flowinternet.net/)