Could it be your power supply the LG 4163b will draw a lot more amps than your old CDRW drive and if your PSU isnt up to scratch or powerful enough you will experince problems like this. Also who makes your PSU and how many watt is it. If your computer is 2 years old i dont expect it to have a powerful PSU, compaq seem to use pretty low watt PSU's my mates Compaq had a 145Watt PSU for a PIII - 700 MHZ computer which is awfully low, though most stuff was integrated onto the board e.g. Graphics / Sound but expansions would cause problems with such a low PSU, im suprised he was able to add a CDR drive to his computer without problems. (TDK 32x writer)
Try disconnecting one of your drives and see if everything works ok then. Also i would recommend researching about new PSU's for compaq computers as im unsure if they use a properietry design like dell or not. If it is proprietry then pluggin a new PSU in will most likely fry your motherboard, if it isnt then their should be no problems.