Hiya,
everything regarding the entire Tutu installation combined with all the other (minor) mods I have were working perfectly until I had finished Candlekeep library and catacombs and were to return to Baldur's Gate. First time I chose to travel to BG (southern section), the game crashed instantly after the area was loaded ("The application has stopped working.") Trying again from autosave, I traveled to BG S, went through the Iron Throne building, travelled to BG SW planning to visit the Flaming Fist HQ, but right in front of the building (right after seeing a few Flaming Fist soldiers) the game crashed again in the same way. So I tried again, went into the Flaming Fist HQ and upstairs, and this is where I realized something was wrong: Duke Eltan was standing there. I mean Kent (or Belt, whatever his name was) was there, so was the doppleganger healer and Eltan lying on the bed, but the original Eltan was standing there as well. I didn't initiate dialog with him trying not mess anything even more, killed the doppleganger, took Eltan's body to be taken to the HarborMaster and on we went - with one crash on the way to the harbor, again with two Flaming Fist soldiers chasing me.
After those, I got to Undercellar, went on to Ducal Palace and having pissed off some FF soldiers on the way there, they followed me into the Palace. Hilarity ensued as the defendant FF soldiers inside attacked these two aggressors after the doppelgangers there were dead

(I didn't want to touch them in order to a save reputation loss) Maybe a piece of code could be implemented here so you couldn't be followed inside the palace..? Anyway, no crashes since, like not before the whole BG revisited scenario either.
All the crashes were just application hangs, so if there even are any dumps or logs you'd like to see I'm happy to deliver them. Oh, and just to mention; all earlier conversations I had with Duke Eltan went properly, without any anomalies or so. Still something points me his - and, well, the Flaming Fist's - way. Looking through here quickly it seems like no one's reported anything similar earlier, so I thought I'd throw in my 2 cents.
I'm running on W7 x64 (not installed under Program Files or anything), using Tutu, Tutufix (latest - where applicable), IPPv4 (mainly BG1 shield animation and paperdoll pieces), Widescreen mod, degreenifier and generalized biffing.