My roblox account wont let me log in

I an having the same problem, on Internet Explorer whenever I type my log in information, it just takes me back to the log in screen. I searched the web and found somone saying they had the problem, so they tryed logging onto Mozilla Firefox and it worked for them... I tryed logging in using the Mozilla Firefox browser and it worked for me to, I can log in, but I cannot play the games!!.