Aperture permissions problem


I have a valid copy of Aperture on my computer. The computer is 27 inch iMac running 10.7.5.

There are two users on the computer, both with admin privileges. Aperture has been working as normal on both with no problems until recently. On one user it is normal.

When I switch users the second user cannot access Aperture. The Dock icon bounces and the Aperture menu appears in the top bar and I get this message box:

View attachment 8382

and there is no alternative library shown in the drop down menu, so it's not like the old fault where you had to open a different library and then switch back.

I have tried several things with no effect.

Checking permissions of Aperture and the Aperture photo library in "Get Info".
Checking computer is "Authorised" in iTunes.
Repairing Disk Permissions.
Redownloading Aperture from the App Store.

Nothing works. Any ideas?
Had a slightly closer look and when Aperture opens for the second user all the menu items are greyed out. So it's not just the library that's not there. And as they are all grey I can't re-link to the library.
Found the answer. Aperture has its own permissions.

Open while holding down the CMD and Option keys and you get a different pop-up offering some buttons to allow you to fix things in various different ways.