I got burnt by this one – all Java processes spin at 100 CPU on update 4.0.6 of VirtualBox.

A work-around is to go to Control Panel / System / Advanced / Environment Variables / System Variables and add a variable called “J2D_D3D” with the value “false”. This will supposedly disable Direct3D in Java.

via #8794 latest update breaks Java on XP guest – VirtualBox.