After some strange things during last 2-3 days ("cinnamon mistakes", black screen - I`d rebooted and everything became OK)
I had received the message:
"Could not grab your mouse.
A malicious client may be eavesdropping on your session or you may have just clicked a menu or some application just decided to get focus.
Try again. <CLOSE>"
What I have to do? Is my computer is infected by virus?