Why won't visual effects work with a dual monitor setup

I am running Ubuntu 10.10 with a Intel 945GME Express Integrated Graphics Controller (rev 03) and I cannot use Visual Effects when I have both monitors turned on.

When I use the Visual Effects control to change it back to Normal or Extra the screens flicker and the checkbox stays on what I selected, but it doesn't actually activate, and when I re-open the dialog, it's back on None.

Is it just that my video card can't handle it, or is there a bug here that needs fixing?

Strange as it looks try to configure the monitor one above the other in the Monitor app, not side by side: ie.

Some low-end graphic cards has a limit on the biggest textures that they can show 2048x2048. If the combined horizontal resolution of both monitors is bigger than 2048 (quite easy with one at 1280xn and the other at 1024) they will not fit on a single texture and Compiz will refuse to work.

But if you put them horizontally they will fit, as usually vertical resolution is not greater than 1024.

It is most likely a bug in the intel drivers, triggering a crash in compiz. You could install compiz-config and see if the screens option under "general" lists multiple outputs.

In any case, I would suggest reporting a bug on launchpad. (see this link).