Error message: The User Profile Service service failed the logon. User profile cannot be loaded.
What it means: The system doesn't allow you to login using your password. You are stuck.
Operating System: Win Vista Home Edition (It seems it happens even in Win 7)
Fix:
1. Start the machine in safe mode
(click F8 during start, and enter the password -in safe mode there is no issue)
2. Start regedit
(in search just type regedit and enter)
3. Go to the following sub registry key
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
4. And check for the following three issues
a. key name ending with a .bak (if yes then check if there is a similar key name without the .bak and make that the .bak and remove the .bak from the original)
b. refcount is 0 (I checked in all the keys under ProfileList and made refcount 0 for all of them)
c.state is 0 ( even for this I checked in all the keys under ProfileList and made state 0 for all of them).
5. Close the regedit and restart the machine.
Additional Resources:
i. A nice video was posted in youtube which I found was quite helpful for many. Click here for it.
ii. From Microsoft site.
