.NET Framework 2.0 SP2 related issue

I installed .NET Framework 2.0 SP2 on my machine and found that my C# ASP.NET application that was running fine started reporting 'Page not found' error. When I clicked 'Submit' button on the login page the application would redirect to 404. To make sure the problem originated because of the SP2, I removed it and found that my application was back to normal. On research I found that Microsoft has released updates to .NET Framework 2.0 SP2. However, that too didnt solved my problem. Ultimately I found that the issue was in the form tag of the login page. The action property was set as “ ”. This was resulting in a page not found error when the page was posted back. .NET Framework 2.0 SP2 didnt liked action=" ". However it is ok if you write action="" or action="#" or action="login.aspx" or remove the action property.