PC reboots continually installing SQL Server 2005 on WinXP

Hi all,

I have downloaded fresh copy of SQL Server 2005 Express Edition from Microsoft Website and started installing. In last step when installation wizard automatically starts the SQL Service, my computer restarts. And after restarts, atleast after 1 minute my system restarts again without any notification. This continues for several times.

Is this due to some problem with windows? But I have formatted and installed windows xp 2 too.

Please anyone, comeup with some solution I would really appreciate.

Regards
LS