What graphics card/chipset do you have? I have the same problem on my Intel 810. I emailed LucasArts tech support, and the Intel 810 is on the list of chipsets not supported, nor does LucasArts plan on supporting it.
I find that saving, exiting and reloading fixes the problem temporarily. Yeah, it's a pain, but EMI is one of the few games that makes it worth it.