Urgent HELP NEEDED

HI I Just Got Windows XP Installed PRO Edition And my computer has turned its self on like 8 times i had to turn it off by the main power last night so i wont wake up to the computer being on i contacted microsoft support and they said get the lastest update i had a at them one was a backdoor i thought because chkdsk runs via cmos bat and software couldnt cause the system to turn on apart being able that the cmos bat boots the system up for software cause im confused on the whole thing thats why i have put the points up really high PLS HELP i wanna sleep and wake up without the computer begining on

I HAVE A AMD ATHLON T/B 1400 512DDR RAM 266 FSB
ETC………. GEFORCE 2 MX200 SD PC133 64 MB
XP PRO

Etc…….. Thanx PLS HELP!