Yes, I did, and everything was perfectly fine. Though I hadn't tried to re-enact the situation which possibly triggered this nullification of cast chances, as my previous save was way back in the game.
Having Julan Ashlander Companion mod, I'd tried to restore attributes with his spell, which, as you correctly guessed, didn't work.
I didn't changed a bit. You see, all of my character's stats remained unchanged, yet cast chances became zero.
I did get over it, though. By uninstalling the game. I was too far in the game and too involved with my character to just abandon him and start a new one. For the time being I'll play some other games, and I'm sure that I eventually will return to Morrowind.
Thank you for replying, huskobar, and good luck with improving GCD!