diff -uprk.orig xorg-server-1.4.2.orig/hw/xfree86/common/xf86RandR.c xorg-server-1.4.2/hw/xfree86/common/xf86RandR.c
--- xorg-server-1.4.2.orig/hw/xfree86/common/xf86RandR.c	2008-06-11 19:27:40 +0500
+++ xorg-server-1.4.2/hw/xfree86/common/xf86RandR.c	2008-09-25 16:54:51 +0500
@@ -171,6 +171,26 @@ xf86RandRSetMode (ScreenPtr	    pScreen,
 	scrp->virtualX = mode->HDisplay;
 	scrp->virtualY = mode->VDisplay;
     }
+
+    /*
+    * The DIX forgets the physical dimensions we passed into RRRegisterSize, so
+    * reconstruct them if possible.
+    */
+    if(scrp->DriverFunc)
+	{
+	xorgRRModeMM RRModeMM;
+
+	RRModeMM.mode = mode;
+	RRModeMM.virtX = scrp->virtualX;
+	RRModeMM.virtY = scrp->virtualY;
+	RRModeMM.mmWidth = mmWidth;
+	RRModeMM.mmHeight = mmHeight;
+
+	(*scrp->DriverFunc)(scrp, RR_GET_MODE_MM, &RRModeMM);
+
+	mmWidth = RRModeMM.mmWidth;
+	mmHeight = RRModeMM.mmHeight;
+    }
     if(randrp->rotation & (RR_Rotate_90 | RR_Rotate_270))
     {
 	/* If the screen is rotated 90 or 270 degrees, swap the sizes. */