crashing at the start of chapter 2

hi, this game has been running fine for me up to the point where guybrush gets his crew and ship, and chapter 2 starts. At this point the music and title for chapter 2 show, and it crashes with the message

'runtime error
program d:\programfiles\steamapps\...
r6025
-pure virtual function call'

i have tried installing direct x and the microsoft net thing (though up to this point the game ran fine without them) which hasn't worked. even tried it in both the classic and new graphic mode both with the same result at exactly the same point in the game.

anyone got any ideas? thanks.

[kalirion]

I get this same error in Chapter 3 when trying to enter the river fork. Local files verified successfully. Does anyone have any suggestions?