Have you tried using your email to login? The only other thing I can think of make a clean install of minecraft (backup your saves folder first). Be sure you have the latest Java as well.
Here is a neat new feature for minecraftforum.net: add the following bbcode to your topic's opening post and the faces of the people that have +repped the post will show up!
[represent]
Here's an example of what it looks like:
You can find a full description of the site and a mini FAQ at represent.mcf.li.
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