You did not give us much to work with, other than mentioning that it's an HP. Is it a notebook? A desktop?
When a PC's first powered up, it goes through the POST cycle (Power On Self-Test).
First, the CPU initializes, and looks to the system's ROM BIOS for instructions which are stored in CMOS. These instructions direct it to find a video adapter, set bus clock speeds, and then check for installed RAM. Then it queries other harware addresss, such as the keyboard controller, drive adapters, ports, etc.
Normally this activity is displayed on the monitor during the POST and boot cycles, but some PC manufacturers (HP,Dell,Acer, etc) hide this behind a splash screen....dumb idea, as now one doesn't really know at which point in the cycle the unit is hanging up at.
If I were to take a guess, I'd say try reseating your system's RAM modules and and add on cards (Video, Sound, etc.)