diff --git a/src/main/java/omero/gateway/Connector.java b/src/main/java/omero/gateway/Connector.java
index 039141d2..6b65edd9 100644
--- a/src/main/java/omero/gateway/Connector.java
+++ b/src/main/java/omero/gateway/Connector.java
@@ -98,6 +98,7 @@
 import omero.log.LogMessage;
 import omero.log.Logger;
 import omero.model.ExperimenterGroup;
+import omero.model.ExperimenterGroupI;
 import omero.model.Session;
 import omero.sys.Principal;
 
@@ -1010,6 +1011,21 @@ boolean needsKeepAlive()
         return elapsed > ELAPSED_TIME;
     }
 
+    /**
+     * Makes sure the ServiceFactory has the correct group context.
+     * This is necessary when sessionID login was used, because all connectors 
+     * are attached to the same session in that case.
+     * @throws ServerError if the group context cannot be refreshed
+     */
+    void refreshGroupContext() throws ServerError {
+        if (entryEncrypted != null) {
+            entryEncrypted.setSecurityContext(new ExperimenterGroupI(context.getGroupID(), false));
+        }
+        if (entryUnencrypted != null) {
+            entryUnencrypted.setSecurityContext(new ExperimenterGroupI(context.getGroupID(), false));
+        }
+    }
+
     /**
      * Recycles the specified service.
      * 
@@ -1064,5 +1080,4 @@ private StatefulServiceInterfacePrx create(String name, boolean secure)
             throw new DSOutOfServiceException("Could not create " + name, e);
         }
     }
-
 }
diff --git a/src/main/java/omero/gateway/Gateway.java b/src/main/java/omero/gateway/Gateway.java
index 5a9e2dee..4e974226 100644
--- a/src/main/java/omero/gateway/Gateway.java
+++ b/src/main/java/omero/gateway/Gateway.java
@@ -1594,6 +1594,13 @@ public Connector getConnector(SecurityContext ctx, boolean recreate,
                     c = null;
                 }
             }
+            try {
+                // In case of sessionID login all connectors are attached
+                // to same session, so need to explicitely change group context.
+                c.refreshGroupContext();
+            } catch (ServerError e) {
+                throw new DSOutOfServiceException("Failed to refresh group context: " + e.getMessage());
+            }
         }
 
         // We are going to create a connector and activate a session.
@@ -1717,6 +1724,11 @@ private Connector createConnector(SecurityContext ctx, boolean permitNull)
                         .getUser().getPassword());
             }
             if (ctx.getGroupID() >= 0) {
+                // if this connector attaches to an existing session, have to make sure
+                // that all stateful services are closed before changing group (see issue #98)
+                for (StatefulServiceInterfacePrx service : client.getStatefulServices()) {
+                    service.close();
+                }
                 prx.setSecurityContext(new ExperimenterGroupI(ctx.getGroupID(), false));
             } else {
                 throw new IllegalArgumentException("must set security context with a valid group ID");