What is a user profile?
Windows builds a profile the first time an account signs in on a computer. The profile has two parts: a folder under C:\Users named for the account, and a registry hive file, NTUSER.DAT, in the root of that folder. At sign-in, Windows loads NTUSER.DAT as HKEY_CURRENT_USER, so per-user preferences, from the wallpaper to persistent mapped drives, come from the profile. Every account that signs in gets its own profile, and a domain user who signs in on ten PCs gets ten separate local profiles unless roaming profiles are in use.
What is inside the profile folder
- Desktop, Documents, Downloads, Pictures, Music and Videos: the personal folders. OneDrive folder backup can move some of them into the OneDrive folder.
- AppData (hidden):
Localfor machine-specific data and caches,LocalLowfor low-integrity apps such as some browser components, andRoamingfor settings meant to follow the user.%APPDATA%opens Roaming and%LOCALAPPDATA%opens Local. - NTUSER.DAT: the user's registry hive.
C:\Users\Default is the template copied to build each new profile, and C:\Users\Public holds files shared by all users. The variable %USERPROFILE% points to the current user's folder.
How Windows tracks profiles
The key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList has one subkey per profile, named with the account's security identifier (SID). Its ProfileImagePath value points to the profile folder. Two subkeys for the same SID, one ending in .bak, are a common sign that Windows could not load a profile and created another.
Symptoms of a profile problem
| Symptom | Likely cause |
|---|---|
| A message says the user is signed in with a temporary profile; the desktop looks new and changes vanish after sign-out | The profile could not load: corrupted NTUSER.DAT, a damaged ProfileList entry, or a file locked by other software |
| Sign-in sits at Welcome for a long time | Very large profile, a roaming profile copying over a slow link, or folder redirection to an unreachable server |
| Settings do not stick, apps reconfigure at every sign-in, Start or search broken for one user | Corrupted profile data |
| The problem disappears when another account signs in on the same PC | Confirms the fault is in that user's profile, not in Windows |
User Profile Service events in Event Viewer's Application log explain most load failures.
Rebuilding a corrupted profile
- Sign in with a different administrator account while the affected user is signed out.
- Back up the user's data from
C:\Users\name: Desktop, Documents, Downloads, Pictures, browser data and anything else they need. Note mapped drives and printers. - Remove the old profile. The clean method is System Properties (
sysdm.cpl) > Advanced > User Profiles > Settings, select the profile and click Delete, which removes both the folder and its ProfileList key. Alternatively, rename the folder (for example toname.old), then export and delete the account's SID subkey under ProfileList. - Have the user sign in. Windows creates a fresh profile from the Default template.
- Copy the personal files back. Do not copy the old
NTUSER.DATor the whole AppData folder, which can bring the corruption back. - Reconnect OneDrive, mail, printers and drives, and confirm no temporary profile message appears at the next sign-in.
Roaming profiles and folder redirection
In a domain, a roaming profile is stored on a server share, copied down to whichever PC the user signs in to and copied back at sign-out. Folder redirection points folders such as Documents at a network share instead of copying them. Both make sign-in depend on the network, which is why they appear in slow sign-in tickets.
User profile on the CompTIA A+ exam
User profiles map to Core 2 (220-1202) objective 3.1, which covers troubleshooting Windows problems, including slow profile loads and profile corruption. Know the profile path, that NTUSER.DAT becomes HKEY_CURRENT_USER, what a temporary profile looks like to the user, and the rebuild order: back up data, remove or rename the profile and its ProfileList entry, sign in to create a new one, then restore files. If only one user on a PC has the problem, think profile; if every user has it, think Windows or hardware.