Zoom issue

[cabfest1963]

Zooming in reveals only a tiny slice of the image at a time, see screenshot. And the editing tools won't function once zoomed in. HELP!

[cabfest1963]

Solved by unchecking "Use Graphics Processor" in Preferences/Performance. Restarted Photoshop and all is well in Zoomland. Wondering if anyone can tell me what negative side effects I should be prepared for by doing this?