Index: kernel/kernel-impl/src/main/java/org/sakaiproject/authz/impl/DbAuthzGroupService.java
===================================================================
--- kernel/kernel-impl/src/main/java/org/sakaiproject/authz/impl/DbAuthzGroupService.java	(revision 310728)
+++ kernel/kernel-impl/src/main/java/org/sakaiproject/authz/impl/DbAuthzGroupService.java	(working copy)
@@ -922,11 +922,13 @@
 			// first consult the cache
 			if (authzUserGroupIdsCache.containsKey(userid)) {
 				uag = (UserAndGroups) authzUserGroupIdsCache.get(userid);
-				List<String> result = uag.getRealmQuery(new HashSet<String>(authzGroupIds));
-				if (M_log.isDebugEnabled()) M_log.debug(uag);
-				if (result != null) {
-					// hit
-					return result;
+                                if (uag != null) {
+					List<String> result = uag.getRealmQuery(new HashSet<String>(authzGroupIds));
+					if (M_log.isDebugEnabled()) M_log.debug(uag);
+					if (result != null) {
+						// hit
+						return result;
+					}
 				}
 				// miss
 			}