CS5 has suddenly started opening files with the default magnification of 0.12%. This means images appear as tiny specks of dust in a very small window and typing 'cmd-0' has no effect. Typing 'cmd-1' does enlarge the image to actual pixels but the window stays postage stamp size and has to be manually dragged larger. Typing 'cmd-0' again at this stage returns us to 0.12%.
Resetting the zoom tool or anything else I can think of has no effect.
Any suggestions gratefully received.
Are you using a Mac and have dragged the bottom of the Ps Application Frame up to the top of the screen to try to remove it instead of unticking "Application Frame" in the Window menu?
If yes, then click the maximise button (with '+' symbol when you mouseover it and usually green) at top-left of Photoshop to restore the frame to full size. Now untick Window > Application Frame if you don't want the frame and its gray backdrop.
Thanks Conroy, Application Frame was indeed the problem and now it's fixed.
Much appreciate the quick response.