To clear the message, simply power-cycle the printer. To prevent it from happening in the future, set the PJL password and the Admin Password to your product. Refer to your printer’s User Guide for more information.
Note: This is not a virus/worm and won’t harm your printer. It is simply a control panel “Ready message”.
For Web Jetadmin users, I also recommend document reading this document. HP Imaging and Printing Security Best Practices
Assigning a system password (This is for the LaserJet M575, see your User Guide for instruction specific to your product)
Assign an administrator password for access to the product and the HP Embedded Web Server so that
unauthorized users cannot change the product settings.
1. Open the HP Embedded Web Server by entering the product IP address into the address line of a
Web browser.
2. Click the Security tab.
3. Open the General Security menu.
4. In the Username field, enter the name to associate with the password.
5. Enter the password in the New Password field, and then enter it again in the Verify
password field.
NOTE: If you are changing an existing password, you must first enter the existing password in
the Old Password field.
6. Click the Apply button. Make note of the password and store it in a safe place.