So, how many people are using the store fixes?
These are the mods that fix ea store content bugs. I've narrowed it down to those mods. Take em' out, bug disappears. Put them back in, bug reappears. If someone else has them, could you remove them to test this?
If you don't have them, follow crinrict's advice. It's pretty sound.
Don't bother with you mods folder until you've renamed the entire sims 3 folder in my documents (this is reversible, not permanent). If you do this right, you won't see any save games, your game settings will reset, and the tutorial lessons will start up again.
If this is what you see, start a new game, send your sims to university, and I'm pretty sure your schedule will be there.
If it is, save and quit. Now slowly add mods until the bug reappears (very, very tedious if you have a lot. you'll basically have to restart the game over and over again). Once the bug shows up, you have your culprit.
For me, it was the store fixes, and I am absolutely certain that it was these mods, at least for me.