Because you are not seeing the problem in Safe Mode this tells us that you do have a macro associated with the keyboard shortcut.

The setting could be in the document itself or any of the active templates (Normal, Attached or Addins). You would get a summary of active keyboard customisations if you go to the Print Dialog and change the settings dropdown which says "Print All Pages" to "Key Assignments"

Once you find out which file contains that setting, you can either change the template or go into the Customise Keyboard settings and change the setting in that template

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Andrew Lockton
Chrysalis Design, Melbourne Australia