I've been cracking my head trying to figure out what is wrong with IIS 5.1, whenever i open ANY .asp file (be it the default http://localhost/iishelp) or my own created .asp file, it will give me a "Server Application Error" or "http 500 internal server error". I've looked everywhere high and low and can't seem to find a solution to this problem. Tried reinstalling IIS numerous times, restarting IIS but it doesn't work at all. Anyone knows what's wrong?

After checking the event log, i got this under "System" : The server failed to load application '/LM/W3SVC/1/ROOT/IISHELP'. The error was 'Class not registered '. For additional information specific to this message please visit the Microsoft Online Support site located at: http://www.microsoft.com/contentredirect.asp. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. does anyone have any ideas how to solve this problem?

I had the exact same problem, but I finally found the cause and fixed. I am not saying this will fix yours but it might. The problem was that the account used for IIS services somehow lost the group setting and even after reinstallation of IIS it was not getting reset. So I manually changed the IWAM_NAME (NAME is the name of your computer) to belong to administrators. That fixed the problem. I know it's been a while, but if anyone reads this, good luck.