It most likely means your Windows installation is corrupted or has picked up some malware.
Before doing anything else, try removing half of the installed memory and testing. If it fails, swap installed and removed memory and test again. It's possible you have defective ram. If no help ...
Sony site says you have Windows 7 Home Premium. You should be able to restore the computer to factory state using the Recovery Partition on the hard drive. This is what the Users Guide has to say:
Recovery
How can I create recovery discs?
You can create recovery discs using the VAIO Recovery Center. The discs are used to restore your computer system to its factory default settings. To create the discs, click Start, All Programs, VAIO Recovery Center, and Create Recovery Discs.
If your computer is not equipped with a built-in optical disc drive, you need to connect an external optical disc drive (not supplied).
See the Recovery, Backup and Troubleshooting Guide for more information.
How can I restore my computer system to its factory default settings?
There are two ways to recover your computer system: from recovery discs and from a recovery partition.
See the Recovery, Backup and Troubleshooting Guide for more information.
How can I reinstall the original software and drivers?
You can restore the preinstalled software and drivers using the VAIO Recovery Center. To restore them, click Start, All Programs, VAIO Recovery Center, and Reinstall Programs or Drivers.
See the Recovery, Backup and Troubleshooting Guide for more information.
I believe the
Recovery, Backup and Troubleshooting Guide is on your computer somewhere.