You will want to look in the pxemanager.ini file.
A pxe server was removed and it didnt unregister from the pxe manager. You willl have a rouge GUID in the pxemanager. I do a ctrl + f and input the server name that is showing next to the rouge pxe server with the IP of 127.0.0.1. If you are lucky you can search for 127.0.0.1 and remove any instances of that GUID.
Hope that helps.