i-Lo, the installation order of your mods is wrong. I'm not sure this is indeed the cause of your problem, but I would recommend to reinstall the game and then the mods in the following order:
BG1 Mini Quests and Encounters
Herbs and Potions Add-in
BG1 Unfinished Business
In particular, it is important to install the Widescreen Mod last. Besides, it looks like you may have chosen the wrong installation option for the Widescreen Mod, i.e., unless you are using GemRB, but according to the screenshot you posted this doesn't seem to be the case, you should select
1] for the original Infinity Engine (CHOOSE THIS!)
2] for GemRB
// Log of Currently Installed WeiDU Mods
// The top of the file is the 'oldest' mod
// ~TP2_File~ #language_number #component_number // [Subcomponent Name -> ] Component Name [ : Version]
~WIDESCREEN/WIDESCREEN.TP2~ #0 #1 // Widescreen Mod -> for GemRB: Widescreen Mod v 3.06
Yes, it's definitely the widescreen mod causing this error. It *must* be installed last, and you *must* choose an installation option and resolution that the widescreen mod supports, and never change game resolutions once you have the WS mod installed. Also note Ergos' comment about GemRB.
Ahh you *****.
I read this AFTER I ******* installed the mods for the third time trying to get the damn game to work properly. Now I have to do the installation process all over again.