I was getting the following error when trying to start IIS from my XP machine:

“Unexpected error 0x8ffe2740 occurred“

You can get more information in MS KB @ http://support.microsoft.com/?id=816944

Finally, I discovered that its caused by Skype. It listens to port 80 for incoming call. Now, most of the time IIS starts before Skype starts. So IIS works but if you restart IIS or try to start IIS after Skype is started then you will get this error message.

There are 2 possible solutions:

1. You can change your IIS settings to run in different port (say 81)
For IIS 7, go to IIS Manager, select the website from the left tree view; then goto “Bindings…” from the right side “Actions” pane and edit the port number.

2. You can change your Skype settings
Skype File-> Options -> Connection
Uncheck Use Port 80 as an alternative for incoming connections.

Restart default website.