Document "drawing.dwg" has a command in progress.

Even though this Knowledge Base document Understanding the error " has a command in progress" says it only applies to AutoCAD 2000 and AutoCAD 2000i it can happen also in all later versions of AutoCAD even in AutoCAD 2009.

If you run into this problem you can find some helpful tips in that document. Sometimes when QSAVE does not work you can use SAVE or SAVEAS or click on the x  at the top right corner to either close the drawing or AutoCAD. I've seen this several times after using the 3dorbit command.

Document "<drive>:\<folder>\<filename>.dwg" has a command in progress.
Hit enter to cancel or [Retry]: