Same problem here, and "yes" dual head with two monitors attached.
Each time I fire R4 I get the open GL error.
I'm using a matrox millenium G450, with most recent driver 5.93.9 and hardware acceleration enabled. I'm a bit tenative on the resource side. The G450 only has 16mb onboard, my box is P4 1G, 256 RAM, XP sp2.
I'm anxious to drive this rig, thanx for yer help.