Hi.
I have encounter such a bug. When I walk into Rwhan camp in Iron Mines (Act1) and start to talk with Rwhan my mouse pointer starts to act crazy. I can not control the game. It shakes all over the screen.

I tried few times and this bug repeats every time, one time I have manage to run out of the camp and suddenly cursor start to act normaly, but then after I have killed Rwhan game crashed!

My system is:
Windows XP SP3
2GB RAM
Intel Core Duo T2400 1.83 GHz
ATI mobility radeon x1300

(old but enough for old games IBM T60)

It's been some time since I played Inquisitor for the last time, but can you really talk to the Orc shaman Revkan in that camp? I thought you could just kill him and take the Herbarium from his dead body. Anyway, it's weird that the game crashes at that moment, but that "crazy acting of the mouse pointer" could be the result of the Disorientation spell, just as one loading tip says: "Disorientation makes the mouse cursor shake temporarily!" Maybe the shaman is casting that spell on you... I would suggest you try to raise your Magic Resistance (by equipping an item, drinking the Potion of Magic Resistance, or casting a spell on you, like Shield of Faith) before paying him a visit. Hopefully it will solve the problem.