In Material Settings select create Preview with "LigthWorks Rendering Engine" or uncheck "Disable unrelated controls"
ArchiCAD 12 INT (2156) Win XP sp3
Intel Core2 Quad 6700 / ATI Radeon HD 3870 / Dual LCD screens HP 30" + Dell 30" LCD
and
ArchiCAD 7+8+9+10+11 INT on Win XP sp3