Ooh... for some reason, I don't have a TotSC directory... my badlur's gate directory is all in one.
Also, that arghai.cre file came from my BGII override directory. WEIRD!
The patch numbers are important in this matter then, so they were v(1.3.)5512 for the BG1+TotSC and v(2.5.)26498 for the BG2:SoA+ToB, right? And you do have a Full and Custom install of the games?