Index: if_em.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/e1000/if_em.c,v
--- if_em.c	10 Sep 2009 21:14:55 -0000	1.26
+++ if_em.c	17 Nov 2009 19:27:12 -0000
@@ -1277,6 +1277,17 @@ 
 				    (IFF_PROMISC | IFF_ALLMULTI)) {
 					em_disable_promisc(adapter);
 					em_set_promisc(adapter);
+					/* em_set_multi() will set
+					   multicast promiscuous mode
+					   when there is a large number
+					   of groups.  Therefore, if we
+					   play around with the
+					   promiscuous flags, we should
+					   call em_set_multi to give it
+					   a chance to re-enable
+					   multicast promiscuous mode,
+					   if required. */
+					em_set_multi(adapter);
 				}
 			} else
 				em_init_locked(adapter);
@@ -2555,12 +2566,20 @@ 
 	}
 	if_maddr_runlock(ifp);
 
+	reg_rctl = E1000_READ_REG(&adapter->hw, E1000_RCTL);
 	if (mcnt >= MAX_NUM_MULTICAST_ADDRESSES) {
-		reg_rctl = E1000_READ_REG(&adapter->hw, E1000_RCTL);
 		reg_rctl |= E1000_RCTL_MPE;
-		E1000_WRITE_REG(&adapter->hw, E1000_RCTL, reg_rctl);
-	} else
+	} else {
+		/* Turn off multicast promiscuous mode if it
+		   is on and it doesn't need to be enabled
+		   according to the if_flags. */
+		if ((reg_rctl & E1000_RCTL_MPE) &&
+		    !(ifp->if_flags & (IFF_ALLMULTI | IFF_PROMISC))) {
+			reg_rctl &= (~E1000_RCTL_MPE);
+		}
 		e1000_update_mc_addr_list(&adapter->hw, mta, mcnt);
+	}
+	E1000_WRITE_REG(&adapter->hw, E1000_RCTL, reg_rctl);
 
 	if (adapter->hw.mac.type == e1000_82542 && 
 	    adapter->hw.revision_id == E1000_REVISION_2) {