There was a DigiIntl update thru the Microsoft Update process that causes the NCR 7197 printer to print a series of 50 “Z”s on a reboot or power change.
The fix is simple enough:
Device Manager (Start > Run > devmgmt.msc)
Select “+” next to IonMultiPortSerial
Right click on NCR 7197 Receipt Printer and choose Properties
Select the Driver tab then select Roll Back Driver
Reboot will be required