It's gone. I installed Firefox on my first laptop, started the game, reloaded, got the bug, cleaned cookies, cache and everything, started again, reloaded - there is no bug anymore. Tried several times, no bug.
Update: something is not right, I'll keep digging
Update2: OK, I've narrowed it to only one option :)
Started a new game. Saved, loaded, got the bug. Cleared cookies and cache only, started again, got the bug. Cleared cookies+cache+login information, got the bug. Cleared cookies+cache+login+form & search history, started again, the bug is gone. So it looks like "form & search history" is to blame. Hope it helps :)