[kronolith] "Other events" menu item not visible for all users on all browsers

[Per olof Ljungmark]

Horde 5.0.2
kronolith 4.0.2

Checked at work today with XP and FF 17, the "Other events" menu item
(where you can select weather) was not visible at all for anyone.
Checked with IE8, same result.

Now at home, it is visible for *some* users with FF16 and FreeBSD.

Cleaning various caches does not seem to have any effect. Ajax issue?

Ideas?