catch errors trying to determine fs type

anki/media.py

@@ -72,11 +72,12 @@ class MediaManager(object):
     def _isFAT32(self):
         if not isWin:
             return
-        if self._dir.startswith("\\\\"):
-            # not sure if we can check on a network drive, so just assume no
-            return
         import win32api, win32file
+        try:
             name = win32file.GetVolumeNameForVolumeMountPoint(self._dir[:3])
+        except:
+            # mapped & unmapped network drive; pray that it's not vfat
+            return
         if win32api.GetVolumeInformation(name)[4].lower().startswith("fat"):
             return True