The Aero Flip 2D does not work anymore although the Flip 3D does . When I press Alt+Tab  I only see the classic list of active tasks:
And I cannot use the directional keys to select a task.
Facts about the problem:
Ø  Only one user account is affected.
Ø  The Desktop Composition is active .
Ø  Ctrl + Alt + Tab does not work.
Ø  Ctrl + Win + Tab works and shows the Flip 3D .
Ø  All other Aero effects work well: Flip 3D, Snap, Shake, Peek, ...
Verifications that have already been made:
ü  $> chkdsk /f c:
ü  Aero troubleshooting.
ü  $> sfc /verifyonly
ü  $> gpedit.msc  . Nothing prevents Aero from working properly.
ü  All the relevant services are active: DWM, Themes.
I will only create another user account as a last resort, so I hope someone can help me.