Savegame now crashes after installing fixes

After installing the patch, the fixpack, UB, the widescreen mod and Ghostdog's UI mod, my savegame now crashes the game when entering a building with the assertion error:-

f:\Torment\Source\baldur\Cvisibility.cpp at line number 1528

I've tried uninstalling the mods to no avail, and I've also tried reinstalling the game with no success. Can anyone help?