Sound like a hard drive problem! If you can access to your data then back it up immediately!
- First try to login in a command prompt mode (press F8 during start and select Safe Mode with Command prompt to boot in MS-DOS mode), once in run the command chkdsk /f /r, it will check your hard drive and It'll try to fix bad sectors.
- Secondly (if you can't login)Try with a Live CD like Hiren's Boot CD or Windows MiniPE and run the same Command on it.
- Thirdly try a utility called WD Diagnostic, It's a Western Digital diagnostic tool, and maybe it can fix the problem.
- To discard a Hard Drive failure you can also remove the HD from the laptop and connect it to a normal PC (if the HD is a SATA drive) and try to access your files through the PC OS.
- and try to boot the laptop with a linux live CD like Ubuntu and without a HD connected, if the laptop works well then maybe the HD is broken or the sata/ide port on the motherboard is.
PD: Sorry about my english! I hope you can understand me
Good luck with your laptop! Cheers!