I found out that the problem only occurs in version 5.4.2.
In version 5.4.1.1, I don't have any login problems.

For a solution, see this thread:
http://www.concrete5.org/developers/bugs/5-4-2/login-with-internet-...

I cannot login from IE 9.0.8112.16421; it simply redisplays home page but not logged in. Several users report same problem. Some simply stay on Login page but no "invalid login" message.

I've tried fix mentioned inhttp://www.concrete5.org/developers/bugs/5-4-2/login-with-internet-... but this makes no difference on my machine.

Chrome, Firefox, and Safari all work just fine.

I'm at 5.4.2.1 and System & Maintenance -> Update reports "All available updates have been either downloaded or applied." and "You are currently up to date!" although I believe that there is a 5.4.2.2 available...

Sorry, but I can't confirm this.

I tried IE 9.0.8112.16421 (64-bit Edition, Updateversion 9.0.3) and I didn't have any login problems. I tried 5.4.2.1 and 5.4.2.2 - both worked fine.

I can confirm that I'm having the same issues with IE. Not for sure whats up!?

I am having this same issue even with concrete5 being completely up to date and I have inserted the code into the fix....still no luck. Just get redirected to login page