My projects scene view has gone a little mad. If I try to pan then the scene then move my mouse one pixel then I end up moving the equivalent of about 100 units!
Rotate and Zoom are also quite fast, but not as bad.
Is there a way to adjust the ‘graininess’ of the editor camera movements?
Have you got a modifier key stuck down by any chance? Shift?
Nope. The modifier keys still work, so I doubt there is one stuck. This panning is wildly huge proportions, about 1000x faster than it should be.
It’s really odd because earlier today it was fine. I’ve managed to get the view into a place where I can see most of the scene I am working on, but it would be nice to be able to fly around it 
Pretty weird. And still like that after you quit and re-launch Unity?
I can’t help you, but in the meantime I can suggest selecting an object, and hitting F with the mouse over the scene view, as an alternate way to bring something into view.
Well a restart of Unity didn’t fix it, but this morning it seems to be working okay. Maybe a restart of my machine was what fixed it (which I find very odd).
Thanks for the tip with using F as well, very useful!
The scene view navigation speed is proportional to the distance of the “focus point” (the point around which view rotates). Maybe you have been focused on some very distant object, and then tried panning around?
Just focusing (F) on something more “relevant” will solve the problem.