PS-CS3 V.10 - Cursors

(Using Windows 7 64 bit, 12 GB ram.)  Occasionally, the tool cursors change to an almost unusable tiny cross, regardless of my settings in Preferences.   After closing and reopening PS a few times, it changes back to my settings.   Is there some key I'm inadvertently hitting to make this happen, some way to get the cursor to go back to my display settings?  (Like, hitting Tab makes the toolbar and preferences disappear and reappear.)  Thanks.