Skype and port 80 conflict with IIS
This one bit me yesterday... If you encounter "unexpected error 0x8ffe2740" when trying to start a Web site under IIS, it may be a conflict with Skype using port 80. If so, the solution, which is found on Jon Galloway's blog, is to go into Skype's options and uncheck "Use ports 80 and 443 as alternatives for incoming connections". In Skype 188.8.131.52 this is located under Tools | Options | Connection. You may have to close and restart Skype for the change to take effect.