After many people reporting login problems, I ran into this myself. And since I advised everybody give a detailed report and I didn't see any (if I've just missed it, apologies), here it is.
If I didn't logoff from one computer and I try to login onto another computer (different location, different day, different IP) I get to this window:
From this window, whatever I do, I cannot login.
Attempt 1: fill user name, captcha, click login. This same window comes back.
Attempt 2: fill user name, captcha, click "Join the community". Same window.
Usually after a few attempts also "Don't you think you have enough?" comes out on red background.
Clearing the bitsler cookies was the only way to get back in.
I hope it helps fixing this bug.
I have the same problem back then, but when I set my account to be automatically log-in to Bitsler there seems to be no problem. The only disadvantage about not logging out is your account might not be safe if other people have access to your personal computer. So I would only recommend this for people who has access on their pcs just by themselves. If I didn't logoff from one computer and I try to login onto another computer (different location, different day, different IP) I get to this window:
From this window, whatever I do, I cannot login.
Attempt 1: fill user name, captcha, click login. This same window comes back.
Attempt 2: fill user name, captcha, click "Join the community". Same window.
Usually after a few attempts also "Don't you think you have enough?" comes out on red background.
Clearing the bitsler cookies was the only way to get back in.
I hope it helps fixing this bug.
. In my experience or knowledge about bitsler policy, one must be level 5 or must have wagered 1btc to be able to receive or be a recipient for rains in chat. 
