I could not get this working with the accepted answer, mainly because I did not know where to enter that code. I looked everywhere for some explanation of the URL Rewrite tool that made sense, but could not find any. I ended up using the HTTP Redirect tool in IIS.
- Choose your site
- Click HTTP Redirect in the IIS section (Make sure the Role Service is installed)
- Check "Redirect requests to this destination"
- Enter where you want to redirect. In your case "wwww.mysite.com/menu_1/MainScreen.aspx"
- In Redirect Behavior, I found I had to check "Only redirect requests to content in this directory (not subdirectories), or it would go into a loop. See what works for you.
Hope this helps.