I have an nvidia 8600MGT, 2.1 GHz Dual Core intel processor and 3GB RAM. Oh btw, I am facing this problem only in maya 2011 and not in 2009. In 2009 everything works fine. I have thoroughly checked and matched the settings, but everything seems ok to me. I'll try re-installing, may be it will fix the issue. I'll let you know if this works.