IFrame strikes back

Well, the IFrame bug from last post still exist, and we still don't know what to do about it.
Some good news are that this bug now appears only seldom and we are less concerned about it. We created a random query string that we attached to this frame source url, to make sure that the browser really really really not caching the page. this way the browser thinks its a new page every time. This (at least we think so) lowered to frequency of appearance of the bug to reasonable levels. Yet, the mystery continues...