diff --git a/include/base.h b/include/base.h
index f6abc91..2256ab9 100644
--- a/include/base.h
+++ b/include/base.h
@@ -161,6 +161,7 @@ struct {
     int nmaxThread;
     int nmaxCycles;
     int siteNumber;
+    bool isRunning;
     Scheduler_t *scheduler;
     Supervisor_t *supervisor;
 } typedef Model_t;
diff --git a/include/scheduler.h b/include/scheduler.h
index 0149738..74ea80d 100644
--- a/include/scheduler.h
+++ b/include/scheduler.h
@@ -33,11 +33,24 @@ void SchedInit(Scheduler_t *scheduler);
 // -------------------------------------------------------------------------- //
 static inline void SchedDestroy(Scheduler_t *scheduler)
 {
-    free(scheduler->globalDrawingSpace->space);
-    free(scheduler->globalDrawingSpace);
-
-    free(scheduler->arrowArray->array);
-    free(scheduler->arrowArray);
+    if (scheduler) {
+        if (scheduler->globalDrawingSpace) {
+            if (scheduler->globalDrawingSpace->space) {
+                free(scheduler->globalDrawingSpace->space);
+                scheduler->globalDrawingSpace->space = NULL;
+            }
+            free(scheduler->globalDrawingSpace);
+            scheduler->globalDrawingSpace = NULL;
+        }
+        if (scheduler->arrowArray) {
+            if (scheduler->arrowArray->array) {
+                free(scheduler->arrowArray->array);
+                scheduler->arrowArray->array = NULL;
+            }
+            free(scheduler->arrowArray);
+            scheduler->arrowArray = NULL;
+        }
+    }
 }
 
 // -------------------------------------------------------------------------- //
diff --git a/src/cli.c b/src/cli.c
index 1525b03..892b174 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -104,7 +104,7 @@ void connectedCommunication(int sockfd)
         curLineLength = 0;
         continueReadLine = 1;
         historyModifier = -1;
-        while (continueReadLine && (curChar = getch())) {
+        while (continueReadLine && (curChar = getch())) { //TODO empty line in history
 
             switch (curChar) {
 
diff --git a/src/main.c b/src/main.c
index b1c15d1..3762f50 100644
--- a/src/main.c
+++ b/src/main.c
@@ -53,6 +53,7 @@ int main(int argc, char **argv)
     ServerDestroy(server0);
     ModelSystemDestroy();
     free(server0);
+    server0 = NULL;
 
     return returnValue;
 }
diff --git a/src/model.c b/src/model.c
index 84ea909..2685dc5 100644
--- a/src/model.c
+++ b/src/model.c
@@ -102,22 +102,6 @@ int ModelLoad(int id) // TODO unload !
     // Creating structure for the Scheduler
     knownModel[id-1]->scheduler = (Scheduler_t*) calloc(1, sizeof(Scheduler_t));
 
-    knownModel[id-1]->scheduler->globalDrawingSpace =
-        (Space_t*) calloc(1, sizeof(Space_t)); // TODO free this
-
-    knownModel[id-1]->scheduler->nMaxThread = knownModel[id-1]->nmaxThread;
-    knownModel[id-1]->scheduler->nMaxCycles = knownModel[id-1]->nmaxCycles;
-
-    // Preparing global drawing space
-    ModelPrepareSpace(knownModel[id-1]->scheduler->globalDrawingSpace,
-                      knownModel[id-1]);
-
-    knownModel[id-1]->scheduler->arrowArray =
-        (ArrowArray_t*) calloc(1, sizeof(ArrowArray_t)); // TODO free this
-
-    ModelPrepareArrows(knownModel[id-1]->scheduler->globalDrawingSpace,
-                       knownModel[id-1]->scheduler->arrowArray, knownModel[id-1]);
-
     loadedModel =
         (Model_t**) realloc(loadedModel, ++loadedModelSize * sizeof(Model_t*));
 
@@ -129,14 +113,37 @@ int ModelLoad(int id) // TODO unload !
 
 int ModelRun(int id)
 {
-    if (id <= 0 || id > loadedModelSize) {
+    if (id <= 0 || id > loadedModelSize)
         return 0;
-    }
-    if (!loadedModel[id-1]->scheduler) {
+
+    if (!loadedModel[id-1]->scheduler)
         return 0;
-    }
+
+    if (loadedModel[id-1]->isRunning)
+        return 0;
+
+    loadedModel[id-1]->scheduler->globalDrawingSpace =
+        (Space_t*) calloc(1, sizeof(Space_t)); // TODO free this
+
+    loadedModel[id-1]->scheduler->nMaxThread = knownModel[id-1]->nmaxThread;
+    loadedModel[id-1]->scheduler->nMaxCycles = knownModel[id-1]->nmaxCycles;
+
+    // Preparing global drawing space
+    ModelPrepareSpace(loadedModel[id-1]->scheduler->globalDrawingSpace,
+                      loadedModel[id-1]);
+
+    loadedModel[id-1]->scheduler->arrowArray =
+        (ArrowArray_t*) calloc(1, sizeof(ArrowArray_t)); // TODO free this
+
+    ModelPrepareArrows(loadedModel[id-1]->scheduler->globalDrawingSpace,
+                       loadedModel[id-1]->scheduler->arrowArray,
+                        loadedModel[id-1]);
+
+    loadedModel[id-1]->scheduler->pleaseStop = false;
+    loadedModel[id-1]->isRunning = true;
 
     SchedInit(loadedModel[id-1]->scheduler);
+
     printLog("Model %d launched\n", id);
     return 1;
 }
@@ -156,14 +163,16 @@ int ModelStop(int id)
     SchedWait(loadedModel[id-1]->scheduler);
     SchedDestroy(loadedModel[id-1]->scheduler);
 
-    loadedModel[id-1]->scheduler->pleaseStop = false;
+    loadedModel[id-1]->isRunning = false;
     return 1;
 }
 
 void ModelDelete(int id)
 {
     free(knownModel[id]->name);
+    knownModel[id]->name = NULL;
     free(knownModel[id]);
+    knownModel[id] = NULL;
 }
 
 void ModelShutdown(void)
@@ -190,7 +199,9 @@ void ModelSystemDestroy(void)
         ModelDelete(i);
     }
     free(loadedModel);
+    loadedModel = NULL;
     free(knownModel);
+    knownModel = NULL;
 }
 
 /* -------------------------------------------------------------------------- */
diff --git a/src/scheduler.c b/src/scheduler.c
index f5254d8..496309c 100644
--- a/src/scheduler.c
+++ b/src/scheduler.c
@@ -57,6 +57,7 @@ static Center_t *findWorkArea(Center_t *centersList, Arrow_t *electedArrow,
             || (zmax && (abs(electedArrow->z - currentCenter->z) <= ruleRadius))
             ){
             free(newCenter);
+            newCenter = NULL;
             //printLog("Can't find a free area\n");
             return NULL;
         }
@@ -213,7 +214,9 @@ static void *schedulerMain(void *scheduler)
     printLog("Scheduler #%lu offline\n", args->id);
 
     free(workerArray);
+    workerArray = NULL;
     free(centersList);
+    centersList = NULL;
 
     return NULL;
 }
diff --git a/src/server.c b/src/server.c
index 6c65d63..af13a26 100644
--- a/src/server.c
+++ b/src/server.c
@@ -112,8 +112,10 @@ void *serverCommunicationInstance(void *server)
     }
 
     close(args->sockfd);
-    if (argv)
+    if (argv) {
         free(argv);
+        argv = NULL;
+    }
     printLog("Disconnected from  %s:%d\n", clientIP, clientPort);
     return NULL;
 }