Any suggestions or similar occurrences?
Are you using a Trackpad or a mouse? With a trackpad, it sometimes can happen, that dust or dirt on the surface will simulate a second finger touching the trackpad, and this can cause unintended gestures.
Otherwise I have no idea.
What exactly are you doing in splitview, when the problem occurs? Are you adjusting images or tagging images, or simply browsing?
Sorry hit solved button in error.
Sorry, that cannot be undone. You might want to post your question again in a new dicussion, for with this thread marked as solved, it is not very likely that someone else will look into it.
I have never seen similar happening with a mouse. Does the same happen, when you are browsing a different library? Try to create a new test library, import a few images and see, what will happen, when you are browsing in split view.
If this works well with a new library, try the Aperture Library First AId tools on your main library.
Repair permissions and repair the library: See Repairing and Rebuilding Your Aperture Library: Aperture 3 User Manual
I checked prefs & had "scroll direction natural" turned on, when off the images are stable in Aperture.
That is an interesting discovery. If you can reproduce this error by toggling this options on and off, I'd send a bug report to Apple, so they can fix it. Use the Feedback form:
Merry Christmas to you too!