@Ged27 -- shutdown your computer, by holding-down the ON/OFF button, until it powers-off.
Power-on your computer, and immediately start tapping the ESC key, until you see a start-up menu.
Is the "HP Hardware Diagnostic" an option? If so, choose that option.
Then, choose to run the "Short DST" --> (short meaning a minute or two, DST ==> Disk-drive Status Test).
If it "fails", then your disk-drive is failing, and needs to be replaced.