[fubu5005]

hi there
ive had my xbox modded since feb this year but in the last month i gave my mate my 80 gig and bought a new one. but i also put his 8 gig original hdd into mine after i put evox onto it. anyway my point is my xbox now wont reconise a hdd at all and keeps coming up with hdd error 7 when there is the slayer disc in the drive or have the screen goes half black and when there is no disc in the drive it comes up error 16 dashboard. ive tried 2 different hdd and cant seem to fix it? if any one can help me that would be great