Hope you are doing good.
Please try the below steps to resolve the issue:
(i) Open the Oracle Virtual Box.
(ii) Click on Settings.
(iii) Click on System:
(iv) Now go to processor and make sure PAE/NX is enabled as shown below:
(v) Now click on OK and try to start the Virtual Machine.
Please try this and let us know if the issue persist.
I will wait for your response.