I had a similar problem with Roddybug.
We were fighting several meduseas (medusi?) on the first level south of the Drow lady who gives you the "Party of Drow" quest. Halfway through the fight Roddy drops out of my party. I tried talking to him but nothing happened. I zoomed in on him and saw that he had been petrified. I guess he failed his saving throw.
It can happen to the best of us when you have several opponents using gaze attacks simultaneously. Eventually you will roll a one.
I ran upstairs; bought a Stone to Flesh scroll; ran back and used it on Roddybug. He recovered and rejoined my party.
Cloudy, the Minotaur/Rustmonster crew include a couple of Gorgons. Maybe Roddy failed his save vs. their petrifing breath weapons. [img]graemlins/1ponder.gif[/img]
Something to think about...