I had that bug myself about two months ago. I know how to fix the problem, but it's not pretty. I considered the game to be finished at this point. Thus, I erased the entire BG2 directory. I mean everything, including the saved game directory and dialog.tlk. I reinstalled BG2, TOB, the TOB patch, the Baldurdash fixes, Ascension, Ease, Item Upgrade, Tactics and Sola in that order. It took me almost an hour, but the problem did go away. I just confirmed the results by taking a party through Ascension. No looping. Like I said, not a pretty fix, but it worked.
Wes, any luck finding the problems discussed in my other posts for the Sahu city or the Liches in the tactics mod?