@wintertime
Login problems can be some real shit...
We had some serious problems with Chrome some months ago as slimjim said, but I and many others experienced the same type of problem also with Opera.
So if you're on a Windows-computer, I think that Firefox is about the only browser to be reckoned with when it comes to log on to GH. IE is also useful in terms of GH-login, but it has had some very serious other security problems.
I should say that I haven't bothered to check on new versions of Chrome and Opera the last month. I've got other things to do, and Firefox works hunky dory for me.
But I hope that your problems will get fixed!!!