Have you installed/updated/changed any mod recently?
If so, force update your minecraft.
If this is not the case or force updating doesn't work then you may be frozen/lagged out somewhere.

There are a couple of things you can do.

1. Get on a better computer and log in and move yourself to a safe place.
2. Get someone else to tp you away from wherever you are the moment you log in.
3. get andrew to delete your userfile (your inventory and location will be lost)

 

There is a new java update for 64bit systems out and I had to install the update to log on. The link is below. Hope this helps.

http://www.java.com/en/download/manual.jsp

 

login servers are slow today just keep trying