Hope I'm doing this right.
Start8 menu before error occurs:
https://dl.dropboxusercontent.com/u/3746163/Start8%20-%20Before%20Problem.jpg
Start8 menu after error occurs (not certain what actions are triggering the error condition):
https://dl.dropboxusercontent.com/u/3746163/Start8With%20Problem.jpg
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Classic Shell menu before error occurs:
https://dl.dropboxusercontent.com/u/3746163/Classic%20Shell%20-%20Before%20Problem.jpg
Classic Shell menu after error occurs:
https://dl.dropboxusercontent.com/u/3746163/Classic%20Shell%20-%20With%20Problem.jpg
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What I mean by "the error" is the graphical degradation of the degradation of the text in the Start menu.
With Classic Shell, right clicking on any application pinned to the taskbar produces the problem.
With Start8, there is less certainty as to what provokes the problem: opening and closing a few applications.
In both cases, logging out and logging back in resolves the problem temporarily until it is evoked again.