Problems with Ethereal Form

Everytime my custom unit casts Ethereal Form the game crashes. The spell is set up for the custom unit, but it still crashes. Has anybody ever had this problem before? How did you guys fix it?

Remeber, Ethreal Form, is basicly a Morph spell. One unit has to have Ethreal Form and the other (specified in Ethreal Form) has to have Corprol (sp?) Form.

If either one of the 2 units doesn't have their coresponding abilities, the game will crash. You also have to make sure that the Ethreal Form unit has Ethreal and no attacks.

Thanks, I'll look at it in the morning, I'm guessing my Ethereal form guy won't change back into the right custom unit, so the game crashes when it realizes the custom unit is gone for good.