computer hangs during startup

[dvrrao]

I have intel pentium 4 cpu 2.66 Mhz with win-xp sp2
i have installed a new hard disk 250 GB seagate SATA port
there are already 2 hard disks one 120 GB SATA and one 80 GB PATA(IDE)
now the problem is many times after the power switch is put on the computer hangs with intel mother board startup screen and the hard apears continuously read since the red light glows
only some times by switching off and on the computer starts normally can any body help me to diagnise the problem
thanks
dvrrao

[Monty007]

Have you installed new software or drivers recently? Can you boot into safe mode?