Are you running a macro or program that involves SolidWorks or SolidWorks documents? Only time I have seen this message is from a program we have that performs an action on a drawing. Sometimes the drawing closes prematurely then when the program tries to access the drawing again, this message gets generated. This is just a possibility; I am sure there are other causes for it.
There can be several reason for the error. If you keep on seeing the error then use SOLIDWORKS Rx tool and send the log files to the company (VAR) you've bought SOLIDWORKS from.