Using VMWare Fusion 3.1.3 on a late 2011 MacBook Pro with an Intel 3000 graphics card, I had problems with IE9 corrupting graphics, especially rounded corners.
According to this link, changing this registry setting to force IE9 to always use software rendering fixes the problem. I found that in IE's Advanced Settings, it showed that software rendering was enabled (but it was greyed out), and despite the fact it was ticked, the registry setting was set to 0. Quitting IE, changing the registry setting and restarting IE fixed it.
The key is: HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\GPU\SoftwareFallback
Set the value to 1 and restart IE9.