Well, not if my command line disappeared. A quick tip... CTRL + 9 puts you back in command. (I found this out the hard way if you are wondering).
Recently a user here had all of his standard parts in the drawing change to anonymous block names when he reopened the drawing. While working with the drawing, all was fine but when he closed and reopened, the parts (eg screws, washers, etc...) would change to names like *U138. Hmmm, after a little checking I found he was saving down to AutoCAD 2000 from Mechanical 2006 (2004 format). This destroys the standard part (proxy part) into a block. Anyway, I just reset his save version in the options and he is back in business. Another day another er.. aa.. another day.