--- a/python/st-util.py	Thu Apr 04 17:58:37 2013 +0200
+++ b/python/st-util.py	Fri Apr 19 12:42:21 2013 +0200
@@ -3,7 +3,7 @@
 import sys
 from PyQt4.QtCore import *
 from PyQt4.QtGui import *
-import stlink, devices, stm32
+import stlink, devices, stm32, usb
 from devices import Interface, Device
 from hexedit import HexEdit
 
@@ -255,9 +255,13 @@
          ip = idx.internalPointer()
          if isinstance(ip, Interface):
             if not ip.IsOpen:
-               ip.open()
-               # Try to get a device:
-               self.mdl.addDevice(ip.createDevice())
+               try:
+                  ip.open()
+               except usb.UsbError as e:
+                  QMessageBox.critical(self, "Error", 'Error opening interface: "{0}"'.format(e))
+               else:
+                  # Try to get a device:
+                  self.mdl.addDevice(ip.createDevice())
          if isinstance(ip, Device):
             self.deviceSelected.emit(ip)
    def openMenu(self, pt):