Menu dropdown lists shaded out as inaccessible

Apologies if this is a repeat, I've searched to no avail.

Has anyone had an issue with Leopard where the menu bar dropdown lists are shaded out as inaccessible?

It doesn't matter whether I'm plugged in or running on battery. The only solution I have found so far is to re-login.

I'm using latest 10.5.2 on a Macbook (Rev. B)

I used Time Machine in the screenshot but it is happening to all of my menus.

 

Noone has any thoughts on this issue? I can't be the only one experiencing this problem.