Advanced vbmenu positioning help please?

[carcomp]

I'm creating a new type of navbar that floats (i.e. docked at the top of the screen) with the rest of the forum beneath it.

Everything is working fine until you scroll the page down some. The popup menus seem to 'go down' the page the further you scroll. Check out the screenshots. I just CAN'T figure this out. I understand how the vbmenu works normally, and how to position (line it up with your text) etc, but this is a new one.

Please help!