Do all machine have the most recent video drivers for their monitor or video adapter?

>Hi everybody,
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>Quite recently we introduced a new problem in our application. When we switch between different containers on a complex multipage pageframe form, each label displays itself twice. If you move the form, this weird visual effect disappears. This effect is only shown in 800*600 resolution. One of our QAs is not having this, but three other PC exibit this behavior. Do you know, what may cause it and what should we do about it?
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>Thanks in advance.