I'm running a 3.0 campaign and have encountered the first game-breaking problem: Haste. I figure I can just switch the spellcasters to using the 3.5 version of the spell if they decide to cast it on somebody; the problem is that the gnome Illusionist and the half-elf Bard/Sorceror both have (something) of Speed, which is giving them the 3.0 Haste effect. In both cases, they paid cash money to have the magic items created for them.
They're out in the wilderness and have just started in on the latest adventure, and won't be hitting a town very soon, so they can't just swap the items out for something of equal value. I'd like to make a change to the way their armor works so they don't rule the combats as badly as they have been (the Bard/Sorceror isn't too bad, because he insists on playing his character about as inefficiently as I've ever seen a spellcaster played, so he kinda needs the extra half-action in order to get his act in gear; the illusionist, however, is casting 4 phantasmal killers in the first two rounds...); however, nerfing their armor down to the point where it really doesn't help them at all just as they get to the dungeon is kinda mean.
I don't believe the 3.5 haste is worth much to spellcasters, and I doubt I'll see much use of it after this, but I've got to get rid of the 3.0 version. It's the grossest spell I've seen since Dimensional Portal from the 2E Tome of Magic.