Sometimes my cursors are normal, for example the crop tool cursor is two overlapping "corner braces" and the Levels black/grey/white selectors are eyedroppers. At other times, for no reason I can tell, they become respectively a dot with four lines spreading from it or a circle with four little knobs ; when this happens, I have tried everything I can think of (including going to Help) but I can not change the cursors back. Then again for no reason, they go back to normal.
I am probably unaware that I am making some command which triggers this. Please let me know what to do next time it happens so that I can get back to "corner braces" and eyedroppers, etc.