Date popup widget freezes when changing month

I have a field that uses date picker from date module. So far worked just fine, but recently started to act weird - it just freezes the browser in some circumstances. No way to debug it - the browser just freezes and I need to kill the window process.

This is the scenario:

1. Create content type with date field (I have date range).
2. Make it use the pop-up calendar widget.
3. Create new node of that type.
4. Click date field to activate the widget.
5. Change month (don't touch days or years, just change month).
6. It freezes.

However when I first select different day, and then change month, everything works fine.

This issue happens in Chrome and Safari. When I tried this with Firefox, it first freezed like with other browsers and then after a while went into infinite loop by showing and hiding the whole widget. It kept showing and hiding it until I closed the window.