Cubase cursor bar Jumps randomaly and plays randomaly (Win8)

Hi,

Yesterday my Cubase cursor bar started to jump randomaly and to play randomaly, and also not play as the cursor moves…

https://www.youtube.com/watch?v=eZXjuTb0sMM&feature=youtu.be

In the video:
0 - 0:34 - cursor moves but no audio comes out
0:34 - audio starts to be heard
0:47 - cursor mooves by itself
1:02 - I moved the cursor to another location and it continues to move forward, but the music stops

What is that??

Thanks