It should be a fault at either the HDD or RAM.
Download and burn the Ultimate Boot CD (Ultimate Boot CD - Overview
) and run MemTest86+ for the ram, and any of the various hard drive diagnostic tools and make a analysis or post ur results here.
Alternatively, once ur computer is booted up, goto run - msconfig - go to the boot tab, then go to advanced options - check the number of processors box and select two from the drop down menu. This way, windows will use all available processors to start.
Also, remove any external devices attached to your computer and then start your windows. This means wireless devices, usb devices, lan cable etc.
If all above fails,
Open msconfig, select diagnostic startup, apply, ok and restart. If issue persists, it is a hardware problem. If this works, then we can blame any of the softwares.