I am trying to do a fairly complex loft, going through 12 sketches. When I am trying to adjust the loft profile, at some point before I am done, the model just disappears. I can see nothing. This seems like a bug kind of thing. I have to close and re-start solidworks, and re-open the model again in order to see it. What gives? I am running SolidWorks 2009 SP3