This topic contains spoilers about the College of Winterhold quest-line.

Edit: Disregard this first post. This is not a bug. However, a bug is listed in the third post of this topic.

So yeah, I just joined the College of Winterhold, and my first assignement is to go listen to an old fart called Tolfdir. During the lesson, he asks me what I think of what he said about security. At that point, the mana bar doesn't show up anymore if I cast a spell, and I can cast a spell like flames for as long as I want.

My character is a level 6 argonian mage with nothing but the Cursed Rring of Hircine equipped.

If you've activated one of the big glowing blue pillars of light, it has a temporary infinite magicka effect. It should go away within about two real-time hours. Just use the time to train your skills.

Indeed, my bad. I remember activating a few of those for a quest of one of the mages there. I didn't notice it gave me a such bonus.

That being said, the effect is listed as Fortify Magicka in the Active Effects, and when I click on it, it says Drain Magicka +25 Magicka for 2 hours. Am gonna edit the first post...