Been a user for some years now, and use Autosketch 8.0 on my desktop PC at work.
Recently seeing a trend - Autosketch will not open some files; looks to associate in a pulldown menu, but no options working. I generated a drawing 4/2012 and it will not open it now (says it's an "old" file in the preview screen).
Some old files from 2003, 2004 come up fine. Others cannot be opened any longer.
Looks to be completely random and seems to think the files are corrupt.