I have done absolutely everything advised on the forums, deleted this and that and utility disk scan, deleted .plist files and many more etc. etc. to no avail.
That does not leave us much to advise, if you already have done absolutely everything, doesn't it?
So I assume, you already did all repair options, tried, if Aperture runs well with a new, empty library, tried, if Aperture runs well in a new user account?
Can we assume, that the problem is caused by your Aperture library, Aperture is behaving well on a new library and in another user account?
If it is your library, that causes constant processing, and all three Aperture repair options did not help, then this can becaused by having imported a corrupted image or an incompatible video.
You can test this by launching Aperture with the shift key held down. If Aperture does not start processing again, it os probably a corrupted image. Then I'd remove the most recent imports and import them again in smaller installments.
Another possibility: If you previously imported an iPhoto library with smart albums,these can cause Aperture to hang. Then I'd delete all iPhoto smart albums and recreate them in Aperture.
After an exhausting and thorough week trying find out the problem with the update I have finally isolated it down to an incompatible file within the Quicktime folder.
The file name is Elgato Turbo.component associated with the Video Capture converter I bought from Apple over a year ago.
It seems that the 3.4.2 Aperture update was not compatible with the file yet. or vice verse!
Shortly after posting this problem on here I received an email from the Aperture development team and was guided through very thorough troubleshooting guides along with sending them database files etc
I was also advised to call Apple technical support who helped me isolate the rogue file error.
I am very grateful to Apple for helping me in this issue as I am on a a deadline to complete a project which means that I can now continue with my work.
I'm sure Apple will post a fix for this soon.
To isolate quicktime files go to Finder -GO -Computer -Library-Quicktime. Make a new folder on your desktop and label it quicktime files. Move all files from this location 'except files starting with Apple xxxx.component' (these are default files)
Restart your computer and open Aperture to see if it's working properly. Start introducing each file,from the new file you created, one by one back into your quicktime folder, restart your compter after every file (I know it takes a while but it's the only way to be sure) and keep checking the operation of Aperture. Eventually you may find that the introduction of a file may interupt the normal function of Aperture like it did for me.
I had scrambled thumbnails and video files which didn't open and disapperaed altogether.
After I took out the 'Elgato' file it all started to work properly. No more lenghthy processing etc. The processing started to fly by very quickly.
I hope this information is helpful to some of you. It may not be this exact file which is corrupting your system but after the 3.4.2 Aperture update the errors started for me so hopefully soon there will be a fix for this in the next update.
thanks to Sean kennedy at Apple in Cork and to david from Aperture develpment in California for helping me with this issue and keep up the good work.
And finally for all you non believers out there... Apple are listening to us!
Happy computing everyone!
PS.Thanks too to Leonie for helping with this matter. It's great to know we can all help each other in times of need..
Thank you for your message and my apologies for the late reply.
The files I have in my library are very varied. The files I created using the Elgato hardware and the software which came with it were not files which I kept in the library as such, instead I kept them on the desktop.
The files are MPEG 4 files.
After the exhausting trial and error I had to endure I came to the conclusion that the file's existence was enough to interfere with the correct operation of Aperture.
I can only assume that the sheer size of my Aperture library, in excess of 40,000 photos and videos, contributed to the inappropriate operation of the program due to the existence of the Elgato file.
I hope this sheds a little more light on it.