Is my Ubuntu hacked (and being controlled by a hacker?)

[Behrang Saeedzadeh]

Hi

Today I suddenly noticed that when I move the mouse suddenly the
cursor moves to random places and some menus, windows, and ... are
being clicked although that I don't press any of the mouse buttons?

Could it be that my system is hacked? If so, how can I be sure that
I'm hacked and how can I stop the hacker from controlling my computer?

As a side not, this all happened shortly after I changed my desktop
theme. Could this be the reason that I'm hacked?

Best Regards,
-- 

Behrang Saeedzadeh
http://www.jroller.com/page/behrangsa