HP desktop will either freeze on startup, freeze after startup or show a f03 error

[WVenezia]

My HP desktop (A pavilion) now fails to function properly. Here are the scenarios I get upon booting up my computer.

1. I press the power button once like normal, and a blue box on a black screen appears, showing a rigid disk not found error screen (f03)

2. I press the power button once like normal, and I get a blue recovery screen saying "Windows hasn't loaded correctly" and shows me the options to either restart my PC or view advanced restoration options.

2a. By choosing the restart option, I get a blue screen for a split of a second before being taken again to the rigid disk error screen

2b. If I "continue to windows" in the advanced options tab, it either brings me to the rigid disk error from above or it effectively takes me to the menu screen, which will probably freeze after one minute

3. I do manage to get into Windows but my PC freezes after a minute or so and a blue screen appears for a split second, before taking me back to the rigid disk error screen again

[WVenezia]

SOMETIMES the computer manages to flawlessly boot and I can use it for long without it wreaking havoc

[TheOldMan]

With the error being F03, that means the error is being detected on a different drive that what is the normal boot disk.  Please post the model number of this PC.  If you know the configuration of this PC, please post that - as that error is an indication multiple drives, with the error in the third or fourth drive.  Typically the boot manager resides on the first drive or possibly the second drive if there is a Optane present.  Check for a memory card in the card reader and if a CD/DVD drive, for a disk in that drive.

To verify the devices, run the Diagnostics routine.

To run the Diagnostics routine, Start tapping the Esc key BEFORE starting the PC and then press the start button.
Keep tapping the Esc key until a popup menu shows. Then pick Diagnostics from that popup menu, F2.
Report back with the results and the model number of the PC.