I'm doing the Lost Histories quest, where you need to go to Skingrad to find a book.

Problem is, whenever I approach the area where Amusei talks to you after the prison-break, the game crashes. I've tried approaching the area from multiple directions, but no luck. Instant-crash when I try to exit the castle courtyard gate to the bridge. Since I have TIE and Better Cities, I have a few other options for getting out of the castle, but whenever I approach that cell where Amusei would update the questline and let me know where the book is hidden, I get a crash.

What can I do to move forward here? I'm on PC, so I would think a console command could allow me to continue in the questline. What would work best, preferably without screwing up the rest of the Thieves Guild? I'm kind of worried because Amusei plays a recurring role...

Any help is much appreciated.

If I were you I'd backup my game saves and reinstall. However, if you go here: http://www.uesp.net/wiki/Oblivion:Lost_Histories
you can use the SetStage info shown on that page to advance the quest.

Why do you think a reinstall would be necessary? Just to fix this, or because this issue is a symptom of a bigger problem?

Is specular lighting turned off in your Oblivion.ini? If so, try setting bDoSpecularPass=1 and see if that makes a difference.

I've never played around with the ini before. Dumb question: is that just a text file located somewhere in the Oblivion or Oblivion/Data folder?