Using PowerPoint triggers traceback (String error?)

[Azaziah]

When PPT is used for presentation playback:

Trunk rev 2677 / Win 8.1

Traceback (most recent call last):
  File "E:\bzr\openlp\trunk\openlp\core\lib\mediamanageritem.py", line 466, in on_double_clicked
    self.on_live_click()
  File "E:\bzr\openlp\trunk\openlp\core\lib\mediamanageritem.py", line 507, in on_live_click
    self.go_live()
  File "E:\bzr\openlp\trunk\openlp\core\lib\mediamanageritem.py", line 534, in go_live
    self.live_controller.add_service_item(service_item)
  File "E:\bzr\openlp\trunk\openlp\core\ui\slidecontroller.py", line 796, in add_service_item
    self._process_item(item, slide_no)
  File "E:\bzr\openlp\trunk\openlp\core\ui\slidecontroller.py", line 851, in _process_item
    [self.service_item, self.is_live, self.hide_mode(), slide_no])
  File "E:\bzr\openlp\trunk\openlp\core\common\registry.py", line 137, in execute
    result = function(*args, **kwargs)
  File "E:\bzr\openlp\trunk\openlp\plugins\presentations\lib\messagelistener.py", line 373, in startup
    controller.add_handler(self.controllers[self.handler], file, hide_mode, message[3])
  File "E:\bzr\openlp\trunk\openlp\plugins\presentations\lib\messagelistener.py", line 80, in add_handler
    self.doc.start_presentation()
  File "E:\bzr\openlp\trunk\openlp\plugins\presentations\lib\powerpointcontroller.py", line 351, in start_presentation
    win32gui.EnumWindows(self._window_enum_callback, size)
  File "E:\bzr\openlp\trunk\openlp\plugins\presentations\lib\powerpointcontroller.py", line 366, in _window_enum_callback
    'right={right:d}, bottom={bottom:d}'.format(left=left, top=top, right=right, bottom=bottom))
ValueError: Single '}' encountered in format string