Hi Jaime,

the key to the solution of your problem are the following code lines:
/* make the dropdown ul invisible */
.menu2 ul li ul {
display: block;
}

.menu2 ul li + li ul {
display: none;
}

The first decleration unhides all gallery pages from the beginning on. The second one hides all pages following the first one. Result: Only the first page is visible from the beginning on. Behavoir of the gallery stays the same. If You leave the menu with the mouse, the first page becomes visible again.

However, in this form, the layout collapses. Why? Because, if you want to hide a page, you just have to set display:none. Whereas, if you want to unhide a page, you have to set much more css attributes which all controll the layout:

.menu2 ul li:hover a {...}
.menu2 ul li:hover ul {...}
.menu2 ul li:hover ul li {...}
...(just watch them all up in the css file)

Just add .menu2 ul li a, .menu2 ul li ul, .menu2 ul li ul li, etc. (all the same, but without :hover at the li) to the selectors above, so that the first gallery page is being rendered correctly.

Example:
.menu2 ul li:hover a, .menu2 ul li a {...}
.menu2 ul li:hover ul, .menu2 ul li ul {...}
.menu2 ul li:hover ul li, .menu2 ul li ul li {...}
...

hope I could help you.
Dave.