In a recent message, wrote in message:
Mila Kunis (who plays Jackie on That 70's Show) took over the voice of Meg when Lacey Chalbert (who also voices Eliza on The Wild Thornberrys) just up and left Family Guy before her contract was up.
My personal opinion but could it be that Nickelodeon might have bullied Lacey Chalbert to quit Family Guy because some of the subject matter on Family Guy could hurt Thornberrys if it ever got out that one of their stars also starred in another animated series which has strong racial and sexual overtones (i.e. all of the Black and Jewish jokes and the almost suggestive bestiality between Brian and Lois).
But at this point I digress and wait for any replies on this board.