dear tech, thanks for your reply.
Already checked the appearence setting
There is no way to repair the installation, the repair option is not shown.
ashdisp.exe will be deleted immediately after a reinstallation
Isn't a problem in my computer, is a new virus or a variant, it delete only executable of any antivirus or antispyware, you try to install, even if I copy, for example, ashAvast.exe in a shared folder, of this machine, from another machine it shall be delete after few second. If I rename ashAvast.exe as ashAvast1.exe it stay there and I can start it, the memory test report no infection, obviously the program can't work in full due the other missing executables.
The setup work fine, but if you have open the destination folder in another windows you can see the load of the executables then in few seconds the deletion of them.
I'm not concerning in reformat the HD but, due the fact I'm consultant, I would like to know what kind of virus can be, just in case one of my customer will be infected.