Fuzzy screen flashing

[Devis]

After many users told me about this I was finally able to see this problem.
In some situation while using the chat and the forum, with Internet Explorer 6, the screen, all the screen, become fool, very fool!
The two windows (chat and forum) flash one over the other with piece of the screen remaining empy (gray). Also the windows deskbar become incomplete, and the only way to stop this is to press CTRL+W, closing one of the IE window.
I've never seen such a bug, this does not happen to users with Firefox (of course).
I've seen this twice and then I was not able toreproduce, but people continue to tell me about this.
Perhaps could be a conflict beetween the chat refresh and the layers/iframes used in the forum.