1. Look at your php error log
2. Look at your Apache error log.
3. Try using this address
http://127.0.0.1/
If that address works it is probably that you are defaulting to IPV6 address's i.e. ::1 and not 127.0.0.1 and wamps security is not configured for IPV6 yet.
If you think this is the problem post a FEW ( NOT ALL ) of the errors from php error log and Apache error log and I will verify that this is the problem and give you a solution.