Using older version of IE

On my Win XP system, I have the IE5 and IE5.5 programs. I used to be able to click on the IE5 and IE5.5 executables and
open those browsers. Now when I do that, I open IE6 anyway.

One tipoff to that is that when I supposedly opened IE5, I saw at the top of the screen the warning (part of IE6/SP
2): "To help protect your security, etc."

I also tested through another service and got: "User Agent: Mozilla/4.0 (compatible; MSIE 6.0;"

So any ideas how to stop this odd behavior on a Win XP Pro system?

Thanks, CMA