On IIS 5.1 ASP Pages Give 404 Error

I have been trying to submit a html form to an asp page. This results in 404 error. When i call a separate asp page with just a response.write or with a small text file i/o operation, it works fine.

But when i use a simple htm form with a text box and submit button gives a 404 error. All the pages exists. I use WinXP Pro/IIS 5.1.

Am i missing anything in settings? I tried restarting, reinstalling IIS and updating the patches to the latest but not of much help.