OIC, that makes sense. Any reason you can't just delete that 'extra' copy of the toolbox from your project drive? or, if it has been modified, move it somewhere?Or, could try something like this:
for dirpath, dirnames, filenames in arcpy.da.Walk(p):
for filename in filenames:
if filename != "con":
arcpy.AddMessage('adding ' + os.path.join(dirpath, filename) + ' to list............')
descr = arcpy.Describe(os.path.join(dirpath, filename))
Since it is looking for that file and is haveing issues with it or the path, this should just make it move on to the next one if the current filename is "con".R_