That error means that the Boot Manager is Missing. This is usualy caused by either a failed hard drive, or a failed attempt at recovery. If you try to do a recovery and then suddenly halt the process, weather on purpose or due to somthing like power failure, then the first bit of the Recovery boot process, the BTMNGR, can be hosed. If this happens then your only option is to order recovery disks from the manufacturer and install the OS that way. These disks will run you about $15-$30

da: http://h30434.www3.hp.com/t5/Operati...I-Do/m-p/34417

L'unica soluzione sembra essere quindi quella di ordinare all'HP un recovery disk