OS Version: Microsoft Windows 7 Ultimate, 32 bit
Processor: Intel(R) Celeron(R) CPU 430 1.80GHz, x64 Family 6 Model 22 Stepping 1
Processor Count: 1
RAM:1.00 gb (894 Mb usable)
Graphics Card: VIA Chrome9 HC IGP Family WDDM, 128 Mb
Hard Drives: C: Total - 39102 MB, Free - 20593 MB;
Motherboard: BIOSTAR Group, P4M900-M7 FE

When i shut down my pc,it shuts down with no problem,but when i restart it,windows begins to load it and suddenly it stops.I need to turn off my pc for 5 MINS,then it loads windows correctly.I can never restart my pc.

The problem is not about windows 7,i had just change from xp.I was having the same problem with windows xp.Everything else is good in my pc,just i'm having this problem.

Please help. It's either the HDD failing ...or the PSU.
Those would be the 1st 2 components i would check...

To test the HDD DLoad and run the long test on the Free diagnostics from the HDD manuf. site...
To test the PSU borrow a known good one of the same or greater wattage and swap it in there...can u provide me with a link so that i can test if my hard drive disk is good?
Run hard drive diagnostics: http://www.tacktech.com/display.cfm?ttid=287
Make sure, you select tool, which is appropriate for the brand of your hard drive.
Depending on the PROGRAM, it'll create bootable floppy, or bootable CD.
If downloaded file is of .iso TYPE, use ImgBurn: http://www.imgburn.com/ to burn .iso file to a CD (select "Write image file to disc" option), to make the CD bootable.
For Toshiba hard drives, see here: http://sdd.toshiba.com/main.aspx?Path=ServicesSupport/FujitsuDrivesUSandCanada/SoftwareUtilities#diagnostic
No.

Because i'm not currently sitting in front of the laptop and i therefore have no idea who manuf. the HDD...I think Sea Tools for DOS will work on non Sagate drives
http://www.seagate.com/gb/en/support/downloads/seatools/
Put it on a CD, USB or floppy.
Warning. Sea Tools for DOS has the potential to write on your drive. So you may want the windows version first.
http://www.seagate.com/gb/en/support/downloads/seatools/