There may be a number of causes for this problem; one certainly is a HDD failure.
Have you tried booting in "Safe Mode"? If so with what result?
Have you tried a "Repair" click here
Not knowing exactly how old the laptop is, have you replaced the CMOS battery? Sometime a bad/weak/flat battery causes such problems.
It could also be a bad connection, a problem with the IDE controller or a simple(?) corrupt system file that would normally be corrected using chkdsk /f /r or sfc /scannow.