Quote from #minecrafthelp IRC chat:
1.6.4 clients are currently receiving Error: Bad login when trying to log in to servers. Please wait patiently as Mojang fixes the issue. My theory is that with the new networking framework, the 1.6.4 server system can't resolve it to the old network code. Basically, the 1.6.4 system can not communicate with the login servers, causing the "Failed to login: Bad login" error.

Every once in a while mojang servers get overloaded, and this is the result. It was happening to me Yesterday, too.

i get bad login mostly in 1.6.4, 1.6.2 but not in 1.7.2 version...

This happend to me It does not work 1.6.4 Try 1.7.2 and it should work.

Weird... it's still going on for me (can't join 1.6.4 servers without trying 50 times, people can't join my 1.6.4 server without trying a bunch of times). Anybody know what the problem is/if Mojang's working on it? I changed my password and it seemed to work for a few minutes but then I started getting the same problem.

Kk cool! Thanks guys

There is a global problem with some servers.

Dinnerbone did something :O
Just keep trying to join the server.

if you're using cracked and you try to log onto a premium server, it won't let you in. but if you use premium, i have no idea what's going on.

Players will still be in because you can still get in, its just about luck, keep trying and you will get in, on the server I'm apart of people have been getting in if they keep trying. And once you're playing be aware you might have to do the same thing again if you leave the server for a little. One of our server staff members tried 20 times and finally got in while others have gotten in right away or with only a few tries.

In the server list, it says the server I want to join has 300 players on and its up :3 ?

Oh well. I've changed my password 156 times already. Whatever

Howdy MC players,

Don't worry. Bad Login probably means that servers are down. Don't go completely dramatic like you have done with changing your password. All it means is that the servers are perhaps down.

Untill later,
~Wolfie

Yeah, having the same problem. Good to know my account is still safe.

For me, it doesn't work but after about five times or so it lets you in.

Even when I try without optifine, it still doesnt work

On the minecraft website, it says all the services are up..

Yeah..... Same Problem Im using optifine and I can't log into ANY servers. It sucks ..

Hopefully

I've gotten this too, I hope waiting it out will help

Same thing happening here.

Anyone know whats causing this issue? I can get on after trying like 100 times but its super annoying

Its annoying as -snip-

same prob here, and the servers I'm trying to get onto are still 1.6.4 and so is the version I'm using

Its working 4 me

Even when I use the normal one it doesnt work...

Yeah, the magic launcher has some bugs and doesn't let anyone login to servers.

you using the magiclauncher? (optifine) if you are go to the normal launcher and it will work

Ah i thought it was my server causing the bad logins Glad to hear its not. well i hope they fix it soon :3

And when I go on 1.7 the server isnt updated..

But in 1.6.4, it doesnt say its 1.7

ugh... well thanks for this post! Now i know im not the only one...

This is happening to me right now as well!I guess we have to wait until it gets fixed :/

Yeah, I'm having issues with this too.

They may be updated to 1.7.2, for my brother a few minutes ago it was saying bad login instead of outdated.

Did you used Nodus before? I had the self problem after using nodus.

Is your account migrated? If it is, you're most likely getting "Bad Login" because some servers pertaining to Mojang account logins have gone down/hiccupped. The same thing happened to me a few minutes ago.