I had this same issue.

Yellow icon on Windows 7 64x fresh install.
Beat my head against the google wall.
Turned off and on services, checked for services...etc.
Come to find out it was a simple fix, that i found using the Windows Error Logs.
The configuration files in the "c:\wamp\alias\" directory were set to allow certain IP addresses to connect to it.
It had parsed in an entry such as this: "Allow from ::1", which Apache didn't understand. i rem'd it and added valid IP's, rebooted, and it is now working....

Notes - you must change this in every config file in the folder.
Le- freaking- sigh.