shutdown

my windows xp professional does not turn off the
computer it just in stead restart. when i go to stand by
or hibernate the computer crashes it stop responding. i
have norton professional antivirus 2004, norton firewall
2003 and roxion easy cd creator basic 5.x??. i dont know
how to resolve these problem i've tryed evey method my
power opption does not show the APM tab . my mother board
support turning off i've a ATX power supply. my system
is P4 1.7 ghz and 512 MB ram and geforce 2 64 mb with
NTFS particion help me please. thank you