Unable to run the program of Diablo III Setup

Hi,
The error page doesn’t seem to be helpful in any way whatsoever.

Diablo III Setup
Failed to run a required program (Agent). Wait one minute and try
again and if that doesn't work please restart your computer and try
again.
Please click the link below for more information or contact Customer
Support if the problem persists.
Error code: BLZPTS00007
I have tried a number of things to rectify the problem, renaming, changing privileges, changing firewall, deleting and redownloading, but nothing has been of any use. Do you know what is going on?
Waiting for your responses.
Thanks.
