My User Profile Service recently stopped syncing photos with Active Directory, upon further investigation the User Profile Service Application – User Profile Incremental Synchronization timer job was generating the following error:
The Execute method of job definition Microsoft.Office.Server.UserProfiles.UserProfileImportJob (ID 5d8ac82b-34f7-49de-83ef-44820a7c9b1c) threw an exception. More information is included below.
Invalid namespace
The way to easily resolve this issue is to rebuild the User Profile Service database, here is how:
http://technet.microsoft.com/en-us/library/ff681014.aspx#resetSync
The Architect Evangelist 
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