Submenus disappearing in Firefox.

Hello I'd like to know if anyone of you have the same problem in your Firefoxes. When I browse through bookmarks and move to lower position the submenus often refuse to open. This MPG video file (~650kb) shows what happes if I expressed myself unclearly.

Kyku,

I don't have that problem on either Firefox I use in either Windows or Linux.

Are you using the latest ff? Perhaps try re-installing it or, if you have a ton of extensions installed, perhaps one them is causing the problem?
Jeremy