Topic Checking for Updates.
ok so theres like a few fixes with this the most common on is to go to local disk -> and then programData -> then delete battle.net folder (do this with wow closed) and then start up the ptr again and should re-download the required things.
to show the programdata folder on windows 7 - go to organize in the top left and then folder and search options -> view tab -> hidden files and folders -> show hidden files.
[this didnt work for me so had to redownload the whole ptr, on another pc and then transfer across with a usb XD (this is like worse case) ]
atleast these are the things that i did - first one worked for me on the beta and 4.2 ptr XD