Start program on PC using Arduino I want to create arduino sketch that start program on my computer (i.e., browser) when I push button on Arduino itself.

Is it possible to make it using Arduino uno? I already know how to make a serial connection between PC and Arduino and use Processing software, but as I know, Processing cannot interact with another programs.
Processing is just Java.  If Java can do it Processing can do it.

And Java can do it.

Just ask Google about the Java ProcessBuilder class.