diff --git a/interface.c b/interface.c
index c8b9bc4e..1fe00113 100644
--- a/interface.c
+++ b/interface.c
@@ -250,7 +250,7 @@ long StartDriveTask(void *obj, SConnection *pCon, char *name, float fTarget)
   pDriv = GetDrivableInterface(obj);
   if(pDriv == NULL){
     SCPrintf(pCon,eError,"ERROR: %s is not drivable", name);
-    return 1;
+    return -1;
   }
   if(pDriv->CheckLimits(obj,fTarget,error,sizeof(error)) != OKOK){
     SCPrintf(pCon,eError,"ERROR: %s cannot reach %f, reason %s", name, 
diff --git a/tasdrive.c b/tasdrive.c
index 852dc1e0..4ba2144f 100644
--- a/tasdrive.c
+++ b/tasdrive.c
@@ -364,6 +364,11 @@ static int startMotors(ptasMot self, tasAngles angles,
    */
   status = self->math->mono->SetValue(self->math->monoData,
 				      pCon,angles.monochromator_two_theta);
+  /*
+    The call to CheckStatus is necessary because the eiger monochromator may not 
+    start until then. Deferred until all parameters are known.
+   */
+  self->math->mono->CheckStatus(self->math->monoData,pCon);
   if(status != OKOK){
     return status;
   } else {
diff --git a/task.c b/task.c
index ad93c6d9..be911cdc 100644
--- a/task.c
+++ b/task.c
@@ -24,6 +24,8 @@
 #define READY 1
 #define WAITING 2
 #define YIELDING 3
+
+#define IDUNDEFINED 0L
 /*--------------------------------------------------------------------------*/
 typedef struct __TaskHead {
   long lID;
@@ -46,8 +48,12 @@ typedef struct __TaskMan {
   pTaskHead pCurrent; /* Think trice before you interfere with this! */
   pTaskHead pHead;
 } TaskMan;
-/*---------------------------------------------------------------------------*/
-static long lIDMama = 0L;
+/*---------------------------------------------------------------------------
+The 7 below solves a subtle bug which occurs when a groupID in user code 
+has been initialized to 0 and starting fails. Then it seems as if this 
+group keeps running. As there will always be some task running at 0. 
+  ----------------------------------------------------------------------------*/
+static long lIDMama = 7L;
 #define  TASKERID 123399
 /*---------------------------------------------------------------------------*/
 
@@ -71,9 +77,10 @@ static pTaskHead MakeTaskHead(char *name, TaskFunc pTask, SignalFunc pSignal,
   lIDMama++;
   pNew->lID = lIDMama;
   pNew->iStatus = READY;
+  pNew->groupID = IDUNDEFINED;
 
   if(lIDMama < 0){
-    lIDMama = 0;
+    lIDMama = 7;
   }
 
   return pNew;
@@ -529,7 +536,7 @@ long GetTaskID(pTaskHead it)
 /*------------------------------------------------------------------------------*/
 long GetGroupID(pTaskHead it)
 {
-  return it-> groupID;
+  return it->groupID;
 }
 /*------------------------------------------------------------------------------*/
 const char * GetTaskName(pTaskHead it)
@@ -569,13 +576,15 @@ int isTaskGroupRunning(pTaskMan self, long groupID)
   pTaskHead pCurrent, pNext;
 
   if (self == NULL) return 0;
+  if (groupID == IDUNDEFINED) return 0;
+
   assert(self->iID == TASKERID);
 
   pNext = self->pHead->pNext;   /* skip dummy task */
   while (pNext != NULL) {
     pCurrent = pNext;
     pNext = pCurrent->pNext;
-    if (pCurrent->groupID == groupID) {
+    if (pCurrent->groupID != IDUNDEFINED && pCurrent->groupID == groupID) {
       return 1;
     }
   }