My first reaction was to say "download the latest and reinstall"! Not an option on this one.
I would go into the extensions manager and disable ALL the QT extensions you can find.
Reboot.
Go back to the extensions folder, not the manager, and delete all the QT extensions in that folder.
Reinstall QT 5 from whatever installer you have.
See how it goes.
Back in the day I did not use QT to view pictures. Instead I used a program called JPEGView which was a great little program and did not have a problem with opening pictures.
Surprisingly, you can still find it. Take a look Here
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Would anyone know an explanation for a strange problem I have had on several machines with QuickTime 4 & 5. It happened originally with our original first model bondi-blue iMac. On installing either of the two programmes to replace QT 3, I found that every other picture clicked on would receive the answer that QT could not find an appropriate decompresser. If one then clicked on the same picture twice (or on any other picture at all) the original picture or the second picture would open without complaint. The ability to open and the failure to do so were always in rigid succession. If one selected 20 pics at once to open, the ability to do so and the failure followed the same rigid pattern. +-+-+-+-+- etc. But the video viewer installed with 4 or 5 worked fine.
The problem is still topical as I have a PowerMac 7100 running OS 8.5 and today I installed QT 5 on it, and immediately the same alternate problem started. Any ideas?

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