Index: madwifi-0.9.4/ath_rate/minstrel/minstrel.c
===================================================================
--- madwifi-0.9.4.old/ath_rate/minstrel/minstrel.c	2007-12-12 05:11:07.000000000 +0100
+++ madwifi-0.9.4/ath_rate/minstrel/minstrel.c	2008-07-24 15:15:41.000000000 +0200
@@ -394,6 +394,9 @@
 	int rc1, rc2, rc3;         /* Index into the rate table, so for example, it is  0..11 */
 	int rixc1, rixc2, rixc3;   /* The actual bit rate used */
 
+	if (sn->num_rates <= 0)
+		return;	
+
 	if (sn->is_sampling) {
 		sn->is_sampling = 0;
 		if (sn->rs_sample_rate_slower)