on 1 of my compaq computers i cant get the os to install. i had fatal hard drive error and my warranty company sent a tech out and installed new hdd, they been out 4 times and istalled the following2 hdds, 2 dvd roms, and my ram. each time when trying to install the os, it says no os found and says press r for full recovery. we insert the disc and it goes to a screeb that has the compaq logo with dots scrolling under it. it will do this for 45 minutes or so the i get a stop error to protect system. they keep plugging parts and no matter what we have tried we cant get the os to install. any suggestions.