Hi Neha,
When you launch the i5Grid, does the MII logon screen open up in the browser before you see a 404 error?
If that's the case, then try to open the MII session in the same browser in which the i5Grid launches.
All in all, the point is that when you launch anything from the workbench, it uses your system's default browser. And if you have your MII session running in some other browser, then you get the MII logon sreen and after giving logging details, 404 error appears.
Hence, the simple solution is to open up your MII session in your default browser.
Let me know if that helped.
Regards,
Rutika Bodas