start up problem

[wakeywhite]

can any one help a computer novice.my problem is my computer keeps almost starting then going back to set up page then it counts down 30 seconds then it looks like windows is going to start then goes off and ges back to set up page .I have a fully upto date internet security package and virus scanner is not showing any problems any ideas .please

[nattab]

sounds like hard drive is knackered, either boot sectors have gone or the hard drive is going