We here at ArmgaSys have started to see a high incident rate of User Profile loading failures.  These failures have different symptoms, but exactly the same root cause.

Symptom #1:  The never ending logon
This symptom is classically described as:

1. You sit down in front of a PC you have logged into every day since you started work
2. You enter your user name and password
3. You are greeted by the “Welcome” screen
4. You watch the “Welcome” screen spinner for hours…. and hours… and hours….

Symptom #2:  New profiles can’t be created
This symptom is classically described as:

1. You have called your client services folks over because of the never ending logon
2. Your client service guy (or gal) logs onto your PC with their administrative account
3. They receive the always entertaining “The User Profile Service service failed the logon.  User profile cannot be loaded”
   

Symptom #3: The event log
Upon reviewing the PC’s event log (which any good Client Service team will do) reveals:

Event 1509, User Profile General
WIndows cannot copy file \Users\Default\AppData\Local\…\sqm-data[SEQUENCE].sql to location [A profile location goes here]
This error may be caused by network problems or insufficient security rights.

DETAIL – Access is denied

Root Cause
The Software Quality Metrics software instrumentation system flubbed up a file in your user’s profiles.
We see this a lot in Visual Studio installs (VS2010 – VS 2013) but have noticed an increase in other Microsoft products.

How to fix
It is simple!  Find and delete the SQM files listed in the event log

-OR- (The more draconian approach)

1. Navigate to C:\Users\Default\AppData\Local\
2. Search for *.SQM (all SQM files)
3. Delete them!

Good luck!