Asp.net 2.0 menu .... In Side update Panel Not working...

[Masudur]

Hi...

I have a asp.net 2.0 menu in my application ... i used the menu in side
a update panel...
the menu items are dynamically generated...
well when mouse hover happens the menu opens up.... but does not
close... if i have only one child menu item .. problem dont occur ...
but if i add two or more child menu item.. this problem again comes
back..
I receive a script error ... "cell 0 is null or not an object"

Thanks for any help
Masudur