IIS is not running as the default web server

Experts,
I’m trying to install Vault using IIS. I keep on receiving the error that “IIS is not running as the default web browser”.
I tried uninstalling and reinstalling the Vault.
No use.
What all things I tried:
1. I checked and turned off the UAC (User Account control) option.
2. Ran regedit and deleted HKEY_LOCAL_MACHINESOFTWAREAutodeskPLM
3. I had Autodesk Vault Test ASP.Net. I have completely uninstalled it.
Techies, please help me with a different solution.

Error: IIS is not running as the default web server
Thanks in advance,
Faye
