Hi all, it WORKS!
Issues seem related to the last version of the bloatware HP Support Assitant, currently version 8.
Well, on my Windows 8.1 64 bit I did not found HP SUpport Assistant in the software uninstall utility. I found HP Support Solutions Framework, tried to uninstall and got the error "impossible to uninstall, the software is required for HP support assistant"...ok HP, thank you very much for you garbage, let's workaround.
Solution 1: UNINSTALL
Download the last version of HP Support Assistant, open the .exe with RAR or 7zip, extract to a folder and launch the uninstaller that you will find inside. This should remove correctly all the HP Support Assistant stuff.
Solution 2: DEACTIVATE
Launch msconfig, go to Servces and deactivate HP Software Framework Service, HP Service, HP Support Solutions Framework Service and HPWMISVC.
Then open the "Services" utility. Select one by one HP Service, HP Software Framework Service, HP Support Solutions Framework Service and HPWMISVC, go to "properties" and set the activation to manual or disabled.
Finally open Task Scheduler, go to the HP folder, then disable all entries in the HP Support Assistant and HP Active Health subfolders.
I tried the second solution and after some day it is still working without any problem!
Umberto