Solved the problem. I downloaded the final release of Mountain Lion (I previously had the gold master installed and hadn't bothered to download the final release) and reinstalled it over my existing gold master install. Worked perfectly after that. Took about 10 minutes to complete. I am not sure whether it was an issue with a corrupt file in the Gold Master or whether it was just an issue with the Gold Master itself but the final release seems to resolve it.
yesterday my problem was solved.
First I reinstalled (and updated) Aperture again, but this did not help.
Then I started from the recovery partition (cmd-r during start) and reinstalled Mountain Lion. No, you won't loose anything (but have a backup anyway!!). I did not have the Golden Master (as TheWrongStuff had), but the "normal" release fom the AppStore. But reinstallation helped anyway!
Now I am able to import again, and play my "old" movies, as it used to be!
Anyway, Apple is interested in my Aperture Library, I will send it to them on Monday. If they find out anything else, I will report here.
Just try to reinstall Mountain Lion, you can't do anything wrong doing this, I hope it works for you, too.
Have a nice weekend!
I've been struggling with this same issue now for a day, and thankfully found this discussion. After re-installing AP 3.3.2 I could not play or import movies. The referenced movie files were fine, but AP was not operating correctly.
So taking Bergmann's and WrongStuff's advice, I re-installed Mountain Lion from the recovery disk. I had to wait about 3 hours for it to finish....but it worked!
The only issue I found was the poster frames (thumbnails) for most of the movies need to be refreshed manually.
BTW, my problem began after I did a full restore from Time Machine, due to a corrupt system file.
I've notified Apple Professional Applications Support of this issue.
Thank you all for taking part in the discussion.
Finaly my issue is solved It seems previous installation was corrupt. I've reinstalled my system just, it took about 40 minutes to complete. Now it has some new changes, but general settings aren't changed.
Before reinstall my login wasn't in the status bar, for example:
Now all works perfectly.
I may have found the root cause. I run a clean script, and one of the tasks is to clean out caches. Specifically, the following location was being cleaned out:
Re-installing Mountain Lion as per Gerhard's post (which resolved the issue for me before I found the cause - thanks Gerhard ), replaces a file in this folder called:
I haven't found the file in any other location, so I've made a copy of it for safekeeping.
So - if you want to test this, move this file from /System/Library/Cache and reboot - it will break Aperture video.
Replace the file and reboot and it's fixed. I haven't investigated what the file does exactly, but open with TextEdit and you'll see it's pretty integral to the system.
Time Machine does not back this location up, so restoring won't fix, however if you have a copy on hand you can replace it and resolve very quickly.
I hope this helps...
Thanks for you time invested in finding the problem!
This indeed worked for me. com.apple.xpchelper.cache is the problem for sure I believe. I could not play my existing videos or import new ones.
Re-installing 10.8.1 does indeed add com.apple.xpchelper.cache to the directory /System/Library/Caches/
link to 10.8.1