Double Clicking a comp in the timeline doesn't work...

Tacroy, I just found your thread and a similar thing happened to me. Double clicking any comp in my project window did NOT open them in the timeline. Had to drop a current comp on a new comp to "pre-comp" it essentially which force opened it in the timeline area. Then i double clicked it inside the worthless pre-comp to open it in timeline then deleted the worthless pre-comp up in the project panel. Also double clicking the mask tool to apply a full size mask to a layer was not working... I searched a ton of threads and eventually just decided to "re-set" my current workspace and everything went back to normal. Not sure what the bug was or where AE got trapped. I even rebooted AE and my computer a few times to return to the same error. Re-setting the workspace was the only thing that fixed it. Not sure if this helps since this happened to you so long ago, but perhaps will help someone else who has the issue

Something has reversed the Alt+click behavior. Restart your system, check your system keyboard settings, trash the AE shortcut files...

Mylenium