Thread:Project:Support desk/Translate: Invalid token (badtoken)

Hi, yesterday I successfully translated the whole page on http://meta.wikimedia.org/wiki/Wikidata/Introduction/cs

Today I wish to make some changes in my translation: I did some edit in the edit window, then I press the Save(a) button and then I become a little box with the message: Invalid token (badtoken) [OK].

Is it any problem with the syntax of my text? Or is it a SW bug? I don't understand what is wrong. I found no description on such event on the helppage Help:Extension:Translate

Thanx!