Please let me know if this works for you guys. I'll be sure to let kepakiano know too!
Sorry for bringing back a months old topic, but I had this same problem a few days ago. Because I don't have Linux, I couldn't try kepakiano's idea, however, inspired by this idea, I copied my savegame just before the Merchant Quarter (at the Iziz Starport) to my Kotor2 install on my Vista Laptop (from a Xp Desktop PC) and tried it. And it worked! Copied back my savegame, saved at the start of the Merchant Quarter to my XP computer, and everything worked fine. Problem solved. Just wanted to let you guys know if you had this problem, this is a possible way to fix it.
I am working on finding the Saved files tonight... I need to try it on a different system and see if this will fix my problem! I have the same EXACT issue! I cannot get into hte marketplace. I have downgraded everything and it will not load!
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