Today I had to install a site on my machine to give the lads a dig out with an issue they were having with one of our projects.
It’s been so long, that I had to basically install everything from IIS to MySQL.
After everything was installed, I just couldn’t get the IIS to start. When trying to start the IIS service, I kept getting this error “Unexpected error 0×8ffe2740″. In the error log, I got another really helpful error… “The service could not bind instance 1. The data is the error code”. Thanks a lot Microsoft engineers, that’s so helpful!
Anyway, I finally got the bottom of it. It turns out that the service won’t start because there is a conflict with some other application running on the same port. After much fishing around on my PC, it turns out that Skype was running on port 80 and IIS was naturally trying to run on that port. Since I knew how to change the port that IIS runs on quite easily, I chose that option, instead of trying to figure out how to change it on Skype.
For those of you who want to do the same, simply go to your IIS manager and on the “Web Site” tab, change the TCP Port to a port of your choice. I changed mine to 8080. So now to view the site I simply type http://localhost:8080/ in my browser! 
Excellent piece of information - Thanks!
Digging around, I found on Skype under “Tools, Options, Advanced, Connection” a checkbox labelled “Use port 80 and 443 as alternatives for incoming connections”. So uncheck that and IIS is back where it should be!