单项选择题 After POST, the error message ‘Invalid system disk. Replace and press any key’ appears. Which of the following is MOST likely the cause?（）

单项选择题 A user states while making several attempts to install a new version of their graphics application,they place the disk in the drive and the LED blinks but nothing happens. Which of the following is the FIRST action to perform?（）

单项选择题 A technician cannot access the print queue to delete a print job. Which of the following is the MOST likely cause of this issue? （）