HP OfficeJet Pro 8500 only prints after reboot of my iMac

I have an HP OfficeJet Pro 8500 (A909a). Not wireless. After I reboot my iMac it'll print for a short period of time, thereafter it will not print or scan unless I reboot. Typical scenario is that I send something to print. After 40 minutes + nothing. I reboot and it starts to print after the chime but before I sign into my account.

Why is this happening? Can anyone help?

Scott