HP Service Advisory c04446835: Distorted Display Colors
HP Elitebook 820 displays distorted colors after exiting hibernation mode. This issue occurs if the computer is using battery power and the battery has a low charge.
Resolution: To resolve this issue, download and install the following Softpaq: ftp://ftp.hp.com/pub/softpaq/sp67501-68000/sp67772.exe
Please note that during the BIOS update be sure the laptop is connected to an AC adapter and does not enter hibernation mode.