Dilettante

A few weeks ago I installed BGT-WeiDU with the BiG World mod and dozens of associated mods, then started playing Baldur's Gate and enjoyed myself immensely.  

Today, I finished Baldur's Gate, and after killing Sarevok, went back to the Duchal Palace and spoke to Duke Belt.  He told me about the mission to Amn and teleported me.  At this point, the game freezes (reliably).  I get the repeated message "party has lost item", then the screen goes blank, then my user interface disappears, leaving a completely black screen.  After about 10 seconds, the bottom right-hand corner of the screen shows up, highlighting a darkened forest area with five or six people standing there, lit by infravision.  All seem to be standing over top of equipment, although it's hard to tell.  They do nothing except make random 'bored' motions.  No buttons I press seem to do anything, and eventually I give up and Ctrl-Alt-Del to get back to my desktop.  

What should I do?  I am eager to begin playing the second game, which I have never completed.  Sadly, I seem to be stuck.  Could anyone help?