Clicking on regions causes them to inadvertently shift in time

Hello,

I've been encountering a nasty little problem. When editing regions in the arrange window, sometimes simply clicking on a region to highlight it will cause it to automatically jump/shift away, out of sync. If I catch the occurrence, an undo command brings it back, but if I don't catch it, I get surprised by out-of-sync track(s) on playback or bounce making for a lot of sync repair work.

Anyone else have this problem? Any answers?

Michael