Next/Previous Unit sometimes doesn't work

[joikm]

I am running a quad core i860, 3 monitors using DirectX 11 mode, full window mode. I've only been playing for a few hours, and I've noticed that the next/previous unit keys (. and ,) often don't work. Sometimes they do (with a nice lag), but often they simply do nothing.

I'm not sure if it's a bug in the game, the fact that I'm running Full Window mode with 3 monitors, or what. Is this a known bug? Has anyone else run into this problem?

Thanks,
Erick