Have you also tried to use the "Repair Permissions" in addition to "Repair Database"?
See Jerry Dalton1's post: Aperture 3.4.5 Slow Performance after update and resolution
If that does not help, reinstall Aperture (depending on your version, as described here: Aperture 3.4: May quit unexpectedly on launch after updating)
If Aperture downloaded with transmission errors, the reinstall might fix this.
As I said I have already tried the Repair Permissions and Repair Database
Sorry, you said "repairing the database and rebuilding", that has a very different effect from "Repairing Permissions". "Repair Database" will not repair the permissions, and neither does "Rebuild". I wanted to be sure, that the permissions also have been repaired.
Yes, running "Repair Permissions" on your entire startup drive using Disk Utility, not just your Aperture Library files can often take care of minor glitches that can sometimes be created during the installation phase. Aperture has many proprietary and system based supporting files that if they don't have the proper permissions, can cause issues. Though, repairing those permissions may not solve the issue you are having, but it is always a good starting point and ususally worth the effort.
Yes, running "Repair Permissions" on your entire startup drive using Disk Utility,
That is o.k. for the start-up drive and for the system files, but for the Aperture library it needs to be done with Aperture's own "repair permissions". That is why this "repair permissions" option has been buit in. Disk Utility knows nothing about the permissions needed for the library.
yeah ... I know ... but sometimes you can repair the permissions on the library file until the cows come home and still not fix the problem ... if the glitch is a permissions problem on Core Image, Aperture Application Support files in the User Library or a number of other files and folders that Aperture needs access to load and run. Most often, these permission issues on the supporting files occur during the installation phase ... especially when multiple updates are installed ... like we saw with the most recent Camera 4.06 and Aperture 3.4.5 being applied by many users at the same time ...
I deleted Aperture and downloaded 3.4.5 from the App Store as a final try at solving my issues. After a few minutes of thinking about things Aperture has opened my library and I seem to be able to make adjustments to images. Many thanks for all your contributions and suggestions above. What is really frustrating is that with Version 3 being so old and having had so many updates there shouldn't be issues like this.
If and when Apple decide to go for Aperture v4 I hope they really iron out the bugs or however much people want to use their products they will see many slip away to use alternative solutions that user communities rate highly.