I have a strange effect in my viewer with some prims. See the attached screenshots. 1 is zoomed in, 2 is zoomed out. When zooming in, some of the prims of these objects disappear. When zooming out, they reappear. It's reproducable from any camera angle and seems to occur at about the same camera distance all the time. Copies of the prims exhibit the same behaviour. These are all "new" prims, created using the build window, and no scripts were ever in them. All prims (both visible and invisible) can still be selected and manipulated. This happens on any region/sandbox I tried, but happens to different prims every time. For every "instance" of the object and for every SL session, the prims that pop are the same. If I change the transparency of the prims to a non-zero value, then back to 0, all prims are visible again for about 3 to 5 seconds, then the popping begins again. I have tried relogging and clearing cache, but this does not influence the behaviour. Graphics preferences and hardware setup do not influence the behaviour. It seems to be related to small (about 0.2m) torusses as it only seems to happen when I have a few of those around. Other small prims don't seem to show this behaviour, unless they are visible with the torusses. Also, it seems the popping only happens more often when Build window is opened. When it's closed, the popping still happens, but not on every zoom in/out. Happens in most recent Second Life viewer and most recent Snowglobe viewer. Happens on two different computers (PC with ATI GPU and laptop with Intel IGP). Other people I've asked to look at it can see it too. It may take a few minutes to start happenning, but it happens every single time, repeatedly and reproducable.