Hi All,
We have also been having this issues with new HP EliteOne 800 units both Windows 7 & 8.1 x64 systems. We have been able to find out the confirmed resolution via our HP Corporate Support Staff.
The problem is how windows handles PS2 devices and this adds a registry entry to sort that out
Fix: http://h20566.www2.hp.com/portal/site/hpsc/template.PAGE/public/psi/swdDetails/?lang=en&cc=us&sp4ts.oid=5272029&swItem=vc_114500_1
Just ignore the SoftPaq decription, as this also works for a HP 8300 All-in-One.
We have tried this now on over 100 computers and it works everytime.
Kind Regards,
FedUni - ICT Services