big float div disappearing under IE

[quenting]

I have some problems using float divs, sometimes and only under IE, if the float part is bigger than the center part, the bottom of the float part (everything under the bottom of the center part) disappears.
Anyone got this problem / knows how to solve it ?

Thanks
Quentin

[redux]

an example of code (or even better, a link to a page) would probably be helpful...

[quenting]

ok, here it is:
example

This page actually has 2 problems :

1) When i mouse over one of the buttons in the center, the left floating frame's bottom is cut.

2) I have some kind of box in the center, with borders/backgrounds. The presence of text in the floating frames messes up the background of the title box (see it doesn't happen in the last box when the right frame is over).

In NS everything is fine (background is ok and no frame disappering).

Thanks a lot for any help.

Quentin