|I'd be inclined to suspect RAM, if situation no better after running the ckhdsk routine as per "Mavis...". If you have two or more RAM sticks installed... reduce to a single (min of 128Meg); trying each in turn...|
Incidentally make/model of PC/laptop is always useful to have here...?
Aslo... likely you have precious files, pics, etc. on the drive that wouldn't like to lose? Presuming so... might be wise to consider safeguarding those first?
Get yoursef a copy of knoppix or ubuntu (linux variants on a cd/dvd) and boot with that. It will allow full acess to th hard-drive and allow you to copy all those files etc. to external media (CD, DVD, another (usb connected) hard-drive).
Verify copies are accessible on at least one other working system; then you can safely set about resolving problems as posted? knoppix.com, ubunty.com both have free ISO files to download and burn to a DVD; then boot wit that DVD.
Ensure the first boot device is set to CD/DVD then HD of course... when booting with a CD/DVD.