The checksum error means the saved data for your bios settings is corrupted, or worse, the actual BIOS is corrupted! The 'Detecting IDE ATAPI device' appears because at a guess, your computer has a disk supplied with it containing a backup BIOS which would be flashed back over your current bios if inserted into the drive and rebooted. Before trying to recover your bios, enter BIOS setup (I think its by pressing F2 on HP, although it could be say F10, F12?), and load setup defaults. Save the settings and exit, and see if it is still doing it. If so, it is a corrupted BIOS and the disk recover method is required. IF you cannot enter the bios to load the defaults due to this error being the first sign of life on your computer, then definitely try the backup bios first, Its unusual for an actual bios ROM to become corrupted (they can be written to for updates). If the backup bios method doesn't work you may have a faulty ROM chip, in which case this is where warranty comes in handy!