Just my two cents...
- Run Memtest86+ to test your RAM.
- Run your hdd brand diagnostic (see HDD diagnostic tools link on my sig)
If both pass with flying colors, try a different operating system using a live CD (try linux live CD - Knoppix or PCLinuxOS). Observe if it will still freeze or ends in error. If in a live CD environment your laptop does not freeze or show any abnormality, do a Windows repair or consider fresh install of Windows.