drop down menu dissapears

[Howits]

Hi all I am a photocopier engineer.

A year or so ago a fellow tech gave me a collection of service manuals with a nice web interface, you can have a look at it here.

https://googledrive.com/host/0B6mecI...0original.html

Note most links dont work as its about 3 gig including the manuals.


I am trying to add "attachment kit" to peripherals.html, but I am doing something wrong as my drop down menu's disappear after a second or so of hovering on them.

https://googledrive.com/host/0B6mecI...ripherals.html

note ""Peripherals original.html" is the working one, "Peripherals.html" is my edit

I have played around with z index but am stuck on this.