Graphical Display Issue

I'm having an issue with an assembly I'm working on. I'll list the symptoms, I believe they're all related.

1) If I isolate a part, when I click isolate, the other parts begin to fade, but at the last second they all re-appear. If I click Rebuild, they all go away.

2) When I insert a new part it's not visible. I have to suppress it then un-suppress it and it becomes visible.

3) If I edit a part within an assmebly, the part dissappears after I edit it. I have to Rebuild to have it show up again.

The assembly isn't too large, but I noticed this problem after I started adding more parts. I've tried restarting SolidWorks and my computer, but that hasn't solved the issue.

Specs:

AMD Athlon(tm) II X4 635 Processor 2.90 GHz

6.00GB RAM

700GB Hard Drive

ATI Radeon HD 5450 512MB

Windows 7 Professional 64-Bit

SolidWorks Premium 2011 x64 Edition SP1.0

Thanks for your help!

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