hi spent hours trying things i solved.
this works:
1.- updated avast to the last date.
2.- downloading the last version of leap motion
3.- unistalling leap motion
4.- Reboot the computer
5.- installing leap motion last version here the machine
will tell you that you have a leap motion reader not a integrated sensor.
6.- reboot and unistalling again
7.- reboot
8.- installing the last version but here when the machine recogonized the sensor
you have to turn it on and off with the space + fn, until it says integrated sensor
9.- reboot
10.- enjoy
too much work but finally the sensor works fine at least for now, the problem
has to be with the avast i supposed. thanks to the guy that post a solution