Grey ex9 renderer

two of my students at the hfg encouter a running vvvv version on their computers but the ex9 renderer remains grey. i figured it might be a directx problem but they claim to have the latest directx installed.
any clues?

what graphiccards? latest drivers? winxp? vista? single/multiple monitors?

Both have Laptops, one is a Mac…definitely no high end grafic cards, winxp, single monitor…
I have to ask them for their cards in detail

A graphic card driver update solved the problem on the Mac.