4gamin: UPDATE:
Ok, I got frustrated and took some time off from TOEE. But I came back and I noticed further that my 8th level cleric can not heal himself or others with spells, cannot heal others with potions, is not effected by sorcerer's spells( like reduce person) and is not subject to the effect of scrolls. My cleric is like a "black hole" into which magic disappears and can also not escape. Needless to say this has made him a less than valuable member of the party. Anyway, still hoping someone might know if this is a bug or something I'm just missing.
Tallima: I've had a ton of weird glitches that disappeared with a fresh install. You may want to give that a try. Keep your saved games and just reinstall the game with a fresh download.
If that doesn't work, then it's probably a corrupt save. If you can back up a few saves, that may fix it. I suspect something was written in his data that doesn't make sense. (can you see any rolls being rolled when he's getting spells cast on him our out of him?)
Otherwise, kill him off and make a new cleric. Use a character editor (I found this thread about them:
http://www.co8.org/forum/showthread.php?t=10467 ) and use it to rebuild your cleric. Then save your game and see how it plays.
ToEE is a great game, but its bugs can be just horrible sometimes. If you're not using Co8, you may want to give it a try. Though I'm not sure if it fixes this issue.
I guess the simplest answer is the best, and although my last good save was quite a ways back, I'm just going to replay things from there. I just hope the same thing doesn't happen again!