Unable to start debugging on the web server. The web server is not configured correctly (asp .net)

Scratched the whole day for this. Hope it would help someone. Here is the problem , solution and some useful links :

PROBLEM -

Site is deployed on QA server or production. One fine morning this error flashes on the site. The whole world comes down crashing at you. Now you try debugging it in your local machine but to no avail. The build is successful but it doesnt run giving a big dialog box with some blah blah error.
PROBABLE CAUSES AND SOLUTION-

1. IIS picks the .net framework version to run the application. If somehow frame work is installed prior to IIS , then IIS and framework linking is ruptured. You need to re-link them.
Solution - go to cmd prompt or VS command prompt ,copy and paste the following :
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis -i
This relinks the iis and framework ......& Bingo !! it will work
2. Some freaking updates are installed on your workstation - either Symantec Endpoint Protection or some Windows update. So when tou try to run the mentioned command u receive an error.
Solution - Uninstall the Updates and run the command again.
3. Some valuable information can be found on the link
http://geekswithblogs.net/TimH/archive/2006/05/29/80002.aspx where a lot of troubled souls are combating with the problem .You will definitely find a solution if the abovementioned solutions didnt help.
4. If none helps , reinstall the frameworks and IIS . Now install IIS first then the frameworks.
5. Still persisting ......... Just pray......
O' Lord Help Me!! :)