Running 2010 latest service pack, 64 bit.

I have an assembly I've been working on for about a week.  As I was building it, had no issues opening it up.  Now, since I've begun detailing parts, any time I attempt to open the assembly directly, SW crashes to desktop.

The only way I seem to be able to open the assembly without crashing is to go into the drawing of the assembly, right-click on the edge of a view of it, and select 'open xxxx.asm', then it opens without trouble.

I've made this assembly entirely in 2010, I did reuse older parts, but have since resaved as 2010 format, though some still probably have links to older assemblies.

Any one ran into this?