A user has a Windows 7 64bit pc (HP Pro series 3405)
AMD A6-3620 2.20 MHz CPU, 4 Gb RAM, 6530D Radeon,
It frequently locks up during the day : the screen goes all white, or all black
The only available is to reboot the PC
I updated the graphics driver, downgraded the antivirus version (ESET Nod32 v7 to version 6)
I checked for malware using Malwarebytes: nothing
Looked on HP support site but didn't find any firmware bios upgrade
any ideas ?