If your installation is stuck at 0% or you are receiving a download failed message, we have found this to usually be attributed to your firewall or security applications, which may be blocking your ability to connect to the ArenaNet servers. We recommend disabling your firewall first and seeing if this fixes the issue. To quickly eliminate whether or not background applications might be interfering with the client, you may want to try disabling background processes which is outlined in the KB article below:
You may also want to check to make sure that you are running the installation as the administrator.
Beyond this, please submit a support ticket to our Technical Support Team so that we may gather some more information from you in order to locate the cause of this issue.
An issue developed in May (2014) with FIOS and Verizon. Here’s a bit of information from our Server Team that may be helpful to those impacted by the problem:
We’ve investigated this and it appears to be a real issue with DNS lookup for some Verizon customers. While editing your host file will work in the short term, it is very risky, as any of those addresses you just hardwired into your OS could change at any time. Even worse, if you’re like me, you’ll forget about editing the hosts file and be really confused in the future when patching stops working.