This is just to give people a heads up in case they come across the same issue. It may be a bug Solidworks needs to sort I don't know.
I updated to Solidworks 2013 yesterday & when I open some of my old models I get some weird looking shadows, lines & what looks like solid planes as you can see from the images below.
If the models are rotated the "oddities" vary by changing shape, size or vanish. I even opened the same model this morning & they appeared different from yesterday as below.
Below is the full model that contains the above assembly.
Below is a sub-assembly from the above assembly that opens without issue, I also have plenty of other large assemblies that open OK.
I have found that by saving the models with issues with Solidworks 2013 seems to solve the problem & they re-open fine, but it would be nice to know if anyone has any ideas what causes this. Below is a 2013 save of the first assembly above.
Hope this helps someone if they have similar issues.
Loving Solidoworks 2013 so far.