PTR servers have gone down, expect a new build to be release shortly.
Unfortunately, we'll have to redownload the entire 16GB client, yet again.
Quote from Zarhym regarding the new build:
"We plan to apply a new build to the 4.0.1 public test realms soon. In order to accomplish our development goals while pushing this next patch, testers will be required to re-patch and re-download all of the PTR client data. This should happen automatically and you can verify this by checking the Launcher when it begins downloading new data. The progress bar should be empty and in the red (Setup) section."
http://forums.worldofwarcraft.com/th...59117084&sid=1