This may be a bit draconian... This will reset ALL of your preferences to default... If you're using Windows, Press, and hold down, Alt, Control, and Shift AS photoshop is losding..... as soon as you see photoshop start to load, hit them keys, and hold them down 'til you are prompted to de;ete current settings... If you're using Mac, hold down Option, Command, and Shift, instead. this's a little after the fact, but... if you have a scroll mouse, rolling the wheel while you are on the image will zoom in/out, centering on the cursor.... from the sound of it it might be more convenient for you. Lou.

"..... and that was when things got interestiing."