I was playing KOTOR and I was fiddling around with the Savegame editor, then I loaded my game, all of a sudden Zaalbar (who was in my party with Carth) didnt load... I was suspicious. Then when I try to walk outside (im in the Manaan Sith base) it takes me back to the main menu! wtf happened?

Sounds like some change you made the game didn't like too much. ;)

Hopefully you backed up your save file before editing like it suuggests in the KSE readme file... right?

-----------------
Before Using KSE
-----------------

Before using KSE, it recommended that you make a backup of your 'saves'
directory, just in case.

For KotOR1, it is also recommended that you download the KSE Fixed Cutscene Files
and place them into your override folder.
Restore your previous save and you should be fine. :)

Edit: Moved to T3-M4's Astromech Droid center as it is the place for tool/editor problems.

This has Happened to me and i didnt back up my save, so i reinstalled it and now i always back up my saves :)

When I'm going to use KSE I save two files -- one called "Test" and another with the location name ("Manaan 2" etc.). With KSE I only mess with my "Test" save. This was after I somehow screwed up and wiped T3 out of my party.