well one suggestion would be to stop using the scroll wheel to zoom. alt + rmb zooms too, ya know. it's also more precise.
as for the alt + lmb dragging problem, the only thing that possibly comes to mind is that the focus of your perspective is no longer the object that you're trying to move the camera around, and so it's rotating just like it should, but the camera's center of interest is in an odd spot so it just seems like it's moving everything... in your perspective (or camera) view, try selecting an object and then pressing the "F" key. this should frame the object and make it the center of interest for your viewport, making rotate act like it should. if that doesn't help, then uhhh... HEY LOOK WHAT'S THAT!?!
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