We inherited magento based shop with GoMage LightCheckout extension (http://www.gomage.com/extensions/gomage-lightcheckout.html) installed. For some reason this extensions doesn't work. In other words, this extension is active and properly installed but we still see default checkout instead of Gomage lightcheckout.
I found that some people reported problems with gomage extension if https/http, www in domains names used.
Cache had been cleared, compilation turned off. We tried to re-install extension, but that did not help us.