My first question is, what is the model and mfg. of your laptop. What windows program are you running?
did you recently get windows Updates. if so, then that may be the root of your problem. I had the same problem with one of my desktops after windows update installed some updates. What you need to do is boot up your laptop, and go into Safe Mode and run Windows Restore. Select the Restore date to a point before the Updates were installed.
if the above is not the case, then your hard drive may be going out.
Some recent updates for Vista and Windows 7 have caused the above problem.