Flash mysteriously and partially disappears – please kindly help if you have time!!

Hello to all supportive and knowledgeable Flash developers around the  world!!

Please please please help me for this very  mysterious and strange problem!! I've tried to shorten the description  to minimum, but please kindly spend 5-10 min to have a read!! And offer  any insights...I am very desperate for some helps

Some backgrounds

I  am implementing a charting tool for my project, which is very similar to  Google’s finance chart but much more tailored-made to meet different  requirements. The charting interface is made up of the following core components:

• Time  selection panel: to change the time span of the chart
• Measurement  points panel: to select different points of measurement
• Chart  area: to display the measurement data of the selected measurement points over the selected time span

For example,  the Apartment’s power administrator can view the total power consumption in Unit 101 of Building A, in the Pacific Apartment’s  complex (a made-up name).

Similarly, the  administrator can also “stack” up charts of multiple measurement  points, having an all-in-one view like below:

Only  the chart is implemented in Flash/AS3, the other panels are JSP, JavaScript and Dojo.

When an  user clicks on a measurement point to add a chart to the chart area, the following things happen in order  (briefly):

1. User clicks on a  link (say,      Total Amps)
2. Dojo event listener attached to the link picks up the mouse click event
3. The Dojo event  listener calls an AS3 method (addChart) through the External Interface to add a chart to the Flash  chart:
4. The Flash chart  picks up the method call, adds a chart to the stage and reposition all charts on the stage. Since the  stage height is fixed at 600 pixels, each chart added will be fitted into the  600 pixels. Eg, 1 chart on the stage = 600 px/chart, 2 charts = 300  px/chart, 3 charts = 200 px/chart…etc.
5. This is what  the Flash chart looks like, when 3 charts have been added, before display the chart on the actually page  (see below)
   
6. Once a chart  has been successfully added to the stage, Dojo will stretch the <div> tag that the chart resides so  that each chart still “looks” like 400 pixels tall. For example, 3 charts on  the stage means each chart is 200 pixels tall, but Dojo will stretch the  entire <div> to 1200 pixels, making each chart look like 400 pixels
7. The above step  is the same concept as resizing the stage

The problem!!!!

When  an user adds more than 7 charts, the 8^th chart will start have  Flash contents disappeared. To be exact, I used firebug to increment the  <div> height, and found that when height exceed 2924 (a magic number) pixels,  Flash contents start to disappear. See below (the red-boxes indicate the  missing contents)

The situation gets worse when continue to add charts, eventually half of the  bottom chart will disappear.

Some pre-work I have done:

• I have unit tested this component in standalone Flash movie, with 3 LCD monitors  totalling 4000 pixels in height. I produced 10 charts in a single flash movie, and  then resized the window from 600px to 4000px, no charts disappear. 
• This happens in all of IE7, IE8, FF3+, and Chrome. Although slightly  different manifestation, but they all have contents mysteriously disappeared.
  
• This also  happens to GOOGLE's finance chart, when you enlarge the chart's  <div> to over 10000 pxs (yet another magic number)
  
• The funny thing is, however, when a graph has been cut in half, the visible half  is still operatable. For example, if the zoom window as been cut in half, I can  still move it, zoom in and zoom out.

Please allow me  to thank you heartfully, if you have finished reading all of the above  information. At this point of time, any useful  suggestions/solutions will be highly appreciated! Please help! THANK  YOU!