It sounds like SolidWorks doesn't like one of your add-ins for some reason. I'd try disabling them one at a time to see if that isolates the culprit.
Can a list of the dlls be had?
My installation is one of a 30 seat system, and I'd been operating on this install since last spring. I would think more likely something got trampled on.
Just to follow up, it took a new system install to fix this.
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