diff --git a/fixtracks/widgets/detectionmerge.py b/fixtracks/widgets/detectionmerge.py
index 0a47705..1a39e57 100644
--- a/fixtracks/widgets/detectionmerge.py
+++ b/fixtracks/widgets/detectionmerge.py
@@ -173,6 +173,11 @@ class MergeDetections(QWidget):
     @fileList.setter
     def fileList(self, file_list):
         logging.debug("MergeDetections.fileList: set new file list")
+        self._files = []
+        self.right_datacombo.clear()
+        self.right_videocombo.clear()
+        self.left_datacombo.clear()
+        self.left_videocombo.clear()
 
         logging.debug("MergeDetections.fileList: setting video combo boxes")
         videoformats = [".mp4", ".avi"]
@@ -207,7 +212,10 @@ class MergeDetections(QWidget):
 
     def on_rightvideoSelection(self):
         logging.debug("Video selection of the %s side", "right")
-        self.right_imagereader = ImageReader(self.right_videocombo.currentText(), self.right_framespinner.value())
+        filename = self.right_videocombo.currentText()
+        if "please select" in filename.lower() or len(filename.strip()) == 0:
+            return
+        self.right_imagereader = ImageReader(filename, self.right_framespinner.value())
         self.right_imagereader.signals.finished.connect(self.right_imgreaderDone)
         self.threadpool.start(self.right_imagereader)
 
@@ -224,8 +232,11 @@ class MergeDetections(QWidget):
             logging.error("Reading frame failed!")
 
     def on_leftVideoSelection(self):
-        logging.debug("Video selection of the %s side", "left")
-        self.left_imagereader = ImageReader(self.left_videocombo.currentText(), self.left_framespinner.value())
+        logging.debug("Video selection of the %s side", "left") 
+        filename = self.left_videocombo.currentText()
+        if "please select" in filename.lower() or len(filename.strip()) == 0:
+            return
+        self.left_imagereader = ImageReader(filename, self.left_framespinner.value())
         self.left_imagereader.signals.finished.connect(self.left_imgreaderDone)
         self.threadpool.start(self.left_imagereader)
 
@@ -243,7 +254,10 @@ class MergeDetections(QWidget):
 
     def on_leftDataSelection(self):
         logging.debug("Data selection of the %s side", "left")
-        self.left_dataframereader = DataFrameReader(self.left_datacombo.currentText())
+        filename = self.left_datacombo.currentText()
+        if "please select" in filename.lower() or len(filename.strip()) == 0:
+            return
+        self.left_dataframereader = DataFrameReader(filename)
         self.left_dataframereader.signals.finished.connect(self.left_dfreaderDone)
         self.threadpool.start(self.left_dataframereader)
 
@@ -257,7 +271,10 @@ class MergeDetections(QWidget):
 
     def on_rightDataSelection(self):
         logging.debug("Data selection of the %s side", "right")
-        self.right_dataframereader = DataFrameReader(self.right_datacombo.currentText())
+        filename = self.right_datacombo.currentText()
+        if "please select" in filename.lower() or len(filename.strip()) == 0:
+            return
+        self.right_dataframereader = DataFrameReader(filename)
         self.right_dataframereader.signals.finished.connect(self.right_dfreaderDone)
         self.threadpool.start(self.right_dataframereader)
 
diff --git a/fixtracks/widgets/taskwidget.py b/fixtracks/widgets/taskwidget.py
index 7734dee..07916f4 100644
--- a/fixtracks/widgets/taskwidget.py
+++ b/fixtracks/widgets/taskwidget.py
@@ -91,6 +91,7 @@ class TasksWidget(QWidget):
             return
         p = pathlib.Path(folder)
         logging.debug("TasksWidget: selected path is %s", p)
+        self._file_list = []
         for d in p.iterdir():
             if d.is_file():
                 self._file_list.append(d)
diff --git a/fixtracks/widgets/tracks.py b/fixtracks/widgets/tracks.py
index 1655ff5..5f19500 100644
--- a/fixtracks/widgets/tracks.py
+++ b/fixtracks/widgets/tracks.py
@@ -409,7 +409,7 @@ class FixTracks(QWidget):
 
     def on_dataSelection(self):
         filename = self._data_combo.currentText()
-        if "please select" in filename.lower():
+        if "please select" in filename.lower() or len(filename.strip()) == 0:
             return
         self._progress_bar.setRange(0,0)
         self._reader = PickleLoader(filename)
@@ -418,7 +418,7 @@ class FixTracks(QWidget):
 
     def on_imageSelection(self):
         filename = self._image_combo.currentText()
-        if "please select" in filename.lower():
+        if "please select" in filename.lower() or len(filename.strip()) == 0:
             return
         img = QImage(filename)
         self._detectionView.setImage(img)
@@ -466,6 +466,10 @@ class FixTracks(QWidget):
     @fileList.setter
     def fileList(self, file_list):
         logging.debug("FixTracks.fileList: set new file list")
+        print(file_list)
+        self._files = []
+        self._image_combo.clear()
+        self._data_combo.clear()
 
         logging.debug("FixTracks.fileList: setting image combo box")
         img_formats = [".jpg", ".png"]