I shut my computer down on December 30th and, when I returned on January 2nd, my AutoCAD files displayed no text.  This includes regular text and dimension text.  It is the same in model space and in paper space.  There is a grip where the text should be in dimensions, but there is nothing where the regular text should be.  When I open the files with DraftSight, the text is all there.  I am not aware of having changed anything. 
 
What may be a clue to what happened is that, when I open a drawing, there are dozens of messages of the form, "** Undefined shape 50", with various numbers including 50.  I'd never seen this.  I can't deduce what is going on and I'm working with DraftSight today, just to get things done.
 
Am I the only one who thinks that AutoCAD 2011 is the worst version ever?  Things come unstuck that were nailed down 20 years ago.

I had a couple of serious problems with 2011 AutoCAD so I went back to 2010.What font are you using?Undefined shape may be referring to a shape file.  Did the text include any special characters?

Thank you for responding.
 
The non-displaying text includes Simplex, Standard and Sans Serif.  There may be other fonts.  There are no characters more exotic than ", ', and /.  Many of the non-displaying text entities have only letters and/or numbers.
 
They are on a common layer, but it is not frozen or off.  The associative dimensions are on the same layer.  The dimension lines and arrowheads are there, but there is a gap where the text should be.  The text is not so small that it can't be seen.  The text appears normally when the file is open in DraftSight.

Can you attach or upload a DWG file to this website?  I'd be willing to look at it.  I have both AutoCAD and DraftSight too.

Run an AUDIT on the damaged file and tell it to automatically fix any errors it finds.  See if that settles your issue.  You might also want to look for a .bak file.  If you find one, change the name to a .dwg with a different filename.  Open that and see if the trouble is still there.Dave.

heinsite2014-01-03 08:47:30