Posting in the Magento forums has been disabled pending the implementation of a new and improved forum solution which should better serve the community.
For new questions please post at magento.stackexchange.com, the community-run support site for the Magento community. We will be providing updates on the new forum solution soon. For questions or concerns please email firstname.lastname@example.org.
Contact your hosting company and ask them if you have a firewall in place for your domain, if so ask them to add a rule to allow all incoming and out going traffic for a short period of time and try the install again.