In IE7-/Win an absolutely positioned box sometimes disappears when in the source code it is the previous or the next sibling of a float. Different test cases and some fixes are shown in IE7-/Win: floats and disappearing absolutely positioned boxes.
The problem seems "time-dependent", i.e. it is influenced by the timing of the arrival of the data to the browser and by the rendering speed. This page is created by a script and the test cases are repeated with and without some added delays in the serving of the html data. The presence of the delays seems to help the appearance of the AP boxes. Of course real network conditions may further interfere, so what you see may differ from my stated results.
In the following test cases a relative positioned box (having hasLayout) contains, in the source code:
The first two cases differ only for the relative order (in the source code) of the AP box and the float. In both of them the AP box disappears (i.e. it is not rendered by IE7-/Win.)
Test 1: The AP box precedes the float.
Test 2: The float precedes the AP box.
Now the same cases, with some added delay (after the AP box.) The markup received by the browser is exactly the same as in the previous two cases. The AP box is now rendered by IE7-/Win.
Test 1b
Test 2b
The same effect can be obtained by some client side delay, obtained for example with javascript: IE7-/Win: Time dependence of the disappearing of absolutely positioned boxes near to floats and clears.