Help!...I am getting a crash in Yaggy battle with ascension and a spell-patch.

[WheyProtein]

Whenever I fight yaga shura, about a minute after he appears the second time (after I wound him, and butcher his army down for a while), the game crashes.  I never had this problem with ascension, but after I have installed this a...small patch for spell fixing, I am getting this problem.  I downloaded this patch from http://www.fortunecity.com/boozers/winelodge/79/; this patch changes the Magic User, Cleric, Druid and Bard spell-progression in BG2 to more closely match that found in P&P D&D (basically it boosts the # of spells mage/cleric/bards can use when their level is high).  I am almost certain this patch is causing the problem. but I obviously do not know why. 

Of course, the best way is not to install this patch at all, but I was wondering if there is any way to keep this patch without crashing the battle (and possibly, future battles after this).  Any help or advise would be appreciated.     

[discharger12]

I had this problem myself, and the only way I could fix it was by uninstalling it, as you said.

Looks like the only way to me.