Strange problem with camera rotate feature

One a single toon of mine I've lost the ability to rotate the camera by holding down the middle mouse button. I don't have this problem on any of my other toons so my mouse is not broken nor are the controls set in the options menu any different for this toon than my others. The only thing different I've been doing with this characters is testing out my AE missions a lot and using the invincible and invisible toggles. Could that be causing this?

Well, it may be a setting you're overlooking or one that SEEMS to be set correctly. I would try this:
1. Log on a toon where the mouse works correctly.
2. Go to MENU, OPTIONS and hit SAVE OPTIONS TO FILE.
3. Switch to the toon with the problem and use LOAD OPTIONS FROM FILE.
4. Profit?

Wow! That did help. Turns out something called free camera movement under mouse options, which I never go near even with a ten foot pole, was enabled. Weirdness but thanks! Funny thing is that in the description of the option in question it just says camera will no longer automatically rotate when in follow mode but I never lost the ability to rotate the camera when following a mob or npc or player, only the use of the middle mouse button/page up bind was affected.