David,
Perhaps a call to Microsoft Accessibility would be useful. They can log in to your machine and check any crash reports and fix things for you if they find problems or at your request, tell you what to fix.
I have had very good success with them. You can call them at 800-936-5900.
It is pretty much impossible to speculate as to where the instability could be without knowing everything about your machine, add ins, etc.
That would take someone logging into your machine and finding the problem point if they can.

HTH,
Richard

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