Problem with writing score.

Hi :)

I have a problem with create new score.
I run Musescore, click "Utwórz nową partyturę"(in english "make new score" or sth like that) and after that I can see this(attachment bottom).

I can't move this or sth.
When I click on this I hear short windows sound.

I can close this only by task manager.

I reinstalled this.
On Musescore and Musescore portable is the same problem.

My OS: Win 7 Home Premium 64-bit. (installed 3 days ago).

Earlier on other HDD I used it and it worked.

Could anyone help me?