This happens when your dialog.tlk file does not match the entries in spells.2da. From the looks of it, are you sure you didn't placed a Kotor 2 spells.2da file in your Kotor 1 override folder? Or accidentally replaced your Kotor 2 dialog.tlk file with the one from Kotor 1? What mods did you installed?
It says that spells.2da tries to read string 124483 while your dialog.tlk doesn't even have 50000 entries.