That can happen if your antivirus software is scanning your computer while you try to log on, tho that's rare at bootup. It can can occur if the "Do not logon users with temporary profiles" Group Policy setting is configured.
It can also happen if the user profile folder was deleted manually. A profile folder that is manually deleted does not remove the Security Identifier (SID) from the profile list in the registry.
If the SID is present in the registry, Windows will try to load the profile by using the ProfileImagePath that points to a nonexistent path. Therefore, the profile cannot be loaded, and you get that error.
The way to fix it is either simple, or a PITA, depending on well versed you are with computers.
First just try restarting the computer and logging on with your user account again. If you restart your computer and it does not resolve this issue, use the following methods to resolve this issue.
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1. Log on to the Computer
Log on to the computer using the Administrator (or an Administrator-level) account. If that doesn't work (because the messed up account IS the Administrator account), reboot it and start your computer in Safe Mode, then log on using the built-in Administrator account.
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2. Go to the Registry
Open the Start menu. In the Start Search area, type regedit and press Enter (if prompted by UAC, click Continue/Yes).
In regedit, go to:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
Expand the ProfileList key and look for the SID key (named "S-1-5"...) with a long number that ends in ".bak".
Click it, and look at the ProfileImagePath value in the right pane to verify that this is the user account profile that has the error.
a) If you have two SID keys with the same number (with one ending in ".bak" and one showing the affected user account in the ProfileImagePath value), continue to Step 3;
b) If you have just one SID key with the ProfileImagePath value showing the affected user account, proceed to Step 4.
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3. Two SID keys with the same number
a) Of the two SID keys that corresponds to the affected user account, right-click the SID key that does NOT end in ".bak" and click Rename.
b) Add .bk to the end of the numbers and press Enter.
c) Right-click the other SID key that DOES end in ".bak" and click Rename.
d) Remove only .bak from the end of the numbers (so that it has the same name as the other SID key did before you renamed it) and press Enter.
e) Now go back and Rename the first one with .bk to .bak now at the end of the numbers and press Enter.
Proceed to Step 5...
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4. Only one SID key ending in ".bak"
a) Right-click the SID key that corresponds to the affected user account and click Rename.
b) Remove only .bak from the end of the numbers, and press Enter.
c) In the right pane, right-click the RefCount value (if none exists, right-click the right pane and click New and DWORD (32 bit) Value, then type RefCount and press Enter), and click Modify.
d) Type 0 into the Value Data textbox and click OK.
e) In the right pane, right-click the State value and click Modify.
f) Type 0 into the Value Data textbox and click OK.
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5. Try logging on again
Close regedit and restart the computer.
You should be able to logon now...
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