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.
Prouver que j'ai raison serait accorder que je puis avoir tort. ~ Beaumarchais