Have XPS I5 Desktop with Windows 10.  Have had the following problem more than several times now. Leave my desktop on all day as I am back and  forth.  On occasion when trying to reactivate the computer from the "sleep mode" I hit any key and the Windows Desktop screen image comes up however the PIN activation window does not come up. The curser is active as is the keyboard but nothing happens.  Without the PIN activation NOTHING happens!  I try unplugging and reconnecting both keyboard and mouse to no avail.  Hit various keys on the keyboard and move the mouse around.  Still Nothing.  After a while I have no choice but to power down the computer and reboot.  In doing this I am afraid of losing or damaging files that were open during the session.   This startup reactivation has now happened probably a dozen times over the last couple of months.  Any advise or comments would be appreciated.