For the sake of your own sanity, you might want to consider either selling off the HP box or changing parts out to build a new stable machine (such as changing the motherboard out for something better).
The last HP I had some years ago (a disposable left over from a development project) was a total nightmare even in Windows due to the BIOS. It was literally the worst PC I ever owned. Looks like you might be getting a similar experience. Ultimately I salvaged the old HP Pavilion for parts, although not much was really reusable due to the shoddy parts they built it with (crappy power supply, non-standards compliant card reader, low end video card, etc etc).