Vertex buffer-size error

[Pnukup]

I've encountered this error while playing HL2:EP1

[IMG]http://img69.imageshack.us/img69/6474/vertexbuffersize.png[/IMG]

I'm not sure what caused it or what section I should ask in, but the box convinced me to ask here.
Is it simply something I can fix in the console in-game or what?

Thanks in advance.

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