USB port not functioning on a user account, works on another This is a 15" MacBook Pro (Early 2011 model).

In one user account, only a single USB port works. When logging into another user account, both USB ports work. What could be causing this? What would you advise as a fix (short of rebuilding the user account)?
I have solved the problem.  I booted into the Lion recovery mode and repaired the disk permissions.  It is now working fine. Hope this can help someone else.