Maybe you’ve had this problem after installing Skype: when you try to launch a Web application in .NET, you get the following errror:

'Visual Studio.Net has detected that the specified Web server is not running ASP.NET version 1.1. You will be unable to run ASP.NET Web applications or services'

There are two reasons for this: either your ASP.NET is not registered with IIS properly or your Web server is being blocked. To determine which is the problem, try to run IIS. If you see this error message, then you’ll know your Web server is being blocked:

'Unexpected error 0x8ffe2740 occured'

This indicates that the port for which IIS is looking (port 80) is already being used by another program.

If you run a freeware program like FPORT in your command prompt (using the following fport/p switch), will most likely reveal that IIS can’t use port 80 because it’s being used by Skype. Skype automatically uses port 80 if it’s not otherwise occupied. Hence the error.

One solution is to stop Skype and restart IIS. Then, later, you can start Skype up again.

But here’s a permanent solution:

1. Open Skype.
2. Go to Tools?>Options?>Connection.
3. Disable the option that says: ‘Use port 80 and 443 as alternatives for incoming connections’.