I would think that HP would have suggested this, but just in case. It is possible that the Boot options set up in the system CMOS are not set up properly, or may have been changed, normaly this wouldnt happen for a new computer, however if it was a demo, and someone reset the boot start up sequence it is a posibility, or if someone after played with the system bios, and reset by accident, I have learned not to be surpirzed by what can be done by accident, and people think they have touched nothing...
First, Try a test, put a floppy disk that you know is bootable into the floppy disk drive. Restart the computer, If the computer wont boot from the floppy disk, then it is probably because the boot sequence has been changed, which is why you may get the error your getting.
You can also skip that step and just go to the system Bios to check the CMOS settings for start up. The way to do that is to Restart the computer, and press F2 and hold on the keyboard, it will get you into the System Bios, then you will see options, you want to go the the CMOS settings. The CMOS start up sequence should be. 1.Floppy drive 2. CD-ROM/DVD drive 3. Hard Drive 4. Other If it is not set up that way, change it to that sequence. then save and quit.
Try that, Restart again, and you should no longer get that error message. If that is ok, and set properly already, then I would suggest making sure that your computer is able to read from all the drives properly. When you talk to HP and the store you got it from, write down dates, and times, and people you spoke with, Just in case there is a problem with mother board, or wiring, that requires you to take it back for repairs.