I guess this post is just to share experience rather than to ask for a fix, since I found the solution.
Today I pressed on the "start" button of gnome in ubuntu, then click on logout. I would wait and wait, then finally, a minute later, the logout panel would appear.
Curious, I loged out. I loged back in, did the same thing, but meanwhile browsed with firefox for answers. I called a terminal from the mini commander applet and deleted .ICEauthority as explained in a mailing list.
When the logout window finally showed up, I closed it, and called it again to check for the timing. It appeared immidiatly. I log out and back in.
I click on log out from the menu, and browse firefox meanwhile. I then clicked on "terminal" from gdesklets, a launcher desklet that looks a lot like Mac OS X's launcher, and the log out box appears imidiatly.
So I log out, log back in, and click on log out, then click on terminal from the desklet imidiatly after that. It appeared again, on the moment that I clicked on terminal.
I closed gdesklets, and remove it from my startup list. I log out, log back in, click on the log out menu thing, and the box appears immidiatly.
It's odd, but I fixed it.