A printer that keeps dropping off and coming back

Since Monday, print jobs to the finance printer at 10.20.0.120 fail several times a day, then start working again on their own. The printer's display shows no errors and its link light never goes out. VLAN 20 is 10.20.0.0/24 with its gateway and an IOS DHCP pool on DSW1. The printer was installed last week by the vendor's engineer with a static address. You work from a PC in the management VLAN, one routed hop away from VLAN 20.