A few months ago I built the computer here: https://forum.solidworks.com/message/425312#425312  pretty much exactly as spec'd out.  Only other thing I did was install an additional HD for storage.  I'm using a FirePro v4900 for video.  It's gotten to a point now that in several of my models when I open a sketch to edit it, I can't close the sketch without SW crashing.  It's pretty much stopped me in my tracks.

New models seem to work for a while then start having issues.

The more complex the design tree, the more likely it is to crash.

New sketches in old models don't seem to be affected as much until they become older sketches.

Relavent information:

Computer spec'd out as previously mentioned.

SW 2012 sp3  - I'm entitled to sp4 but Dassault won't let me download it because I'm not on subscription.  I had it on my old computer but it would not transfer correctly

VisualMill for solidworks 2012 plug in

Video Card driver verified as supported

I've tried repairing the installation - no effect. 

Disabled onboard (motherboard) graphics, no effect.

Aero Theme - no effect.

Non Aero Theme - no effect.

Any ideas and help would be very much appreciated!!!