Worst problem ive ever had. help please.

Ok so ive got my freinds toshiba satellite pro L450D-12X, when i use F8 to do thinks like last known good config and all it jst blue screen and restarts straight away. i try safe mode it just restarts, the only way i can phsyically get on it is with Parted Magic but i cant seem to do what i want to do. when tryna install XP (currently has Windows7) i still get a blue screen, ive tryed the keep hold of 0 (zero) then powering and it doesnt do anythin till i let go then i jst says repair or start normally and none of em work, if any1 can help me with this its so annoying and really dislike Windows 7 because of this! thanks in advance