I can boot into Ubuntu just fine as a guest but it refuses to accept my login name and password that were set during the Wubi install. I reinstalled it again with basic login and password just to make sure and it still won't let me in.
There have been some reports of this. It's not clear what the cause is, but you can try resetting the password as follows:
protected by Community♦ May 6 '13 at 16:31
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