I've had this problem before on another site and the soluation in this thread fixed it:

http://www.concrete5.org/developers/bugs/5-4-2/login-with-internet-...

However, I'm having the same issue again on a new site (5.4.2.2) and when I try to login with Internet Explorer, I'm just redirected to the homepage without being logged in. No errors or anything. If in intentionally input the wrong password, than I get the Incorrect Password error...but a valid login just redirects to the homepage without any sort of login.

My client is not able to get int to make change...and I'm not sure what else to do.

Thanks!