Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.
One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.
Now rename his profile from registry by browsing through Registry Editor (regedit)
HKLM\SOFTWARE\MICROSOFT\WI
in this find the key which got .bak name to the SID.
On right side you will see the values which can help you to identify the faulty profile. There is no harm to delete .bak (All) from there.
After you delete the .bak key you can log in with your profile and it should work.