Unusually this thread is not asking for a solution to a problem but rather describing a solution to one.
A friend of mine who has had a Vaio Laptop (model VPCEE2S1E) for several years had just started to experience system freezes. She would be using the laptop (running Windows 7 Home Premium 64 bit) for either a few minutes or anything up to 3 hours when all of a sudden the system would freeze - the cursor would disappear and the system would lock solid. Sometimes she would be handling email, sometimes the system would be downloading/installing Windows updates, sometimes it would be idle. There was no Blue Screen of Death. The system would just freeze and nothing other than a hard power off would change the situation. Following the hard power off the system would start up again with the normal Widows message saying the system had been abnormally shut down. There were no error messages produced at the time of the freeze and there were no entries in the Windows Event Log for the time the problem occurred.
I tried all sorts of things to resolve the problem including re-installing Win 7 from the Sony Vaio supplied system recovery disks and applying all fixes - sometimes the system would stay up long enough to make a lot of progress and sometimes it would freeze during these updates so the reinstall took quite a while. I also searched the web and found quite a few entries relating to freezes and discussing issues involving a conflict between power management settings and AMD processors and I tried the suggestions of setting power to 100% no matter whether the system was running on battery or mains but nothing worked. I checked the Sony Vaio web site (not a very good site in my opinion) and noticed the BIOS was out of date so I updated this, but again no change. Apart from the BIOS update the only other items on the Vaio web site were a load of proprietary software updates mainly relating to audio/video media applications and a single SATA driver update - however I did not appear to have any disk related problems and anyway I had used the Sony restore media to reinstall the operating system.
I was on the point of giving up when I came across some threads mentioning possible connections between freezing and SATA disk drivers. I checked the Vaio site again and decided that maybe it was worth giving the SATA driver a try. Much to my amazement this appears to have resolved the problem. Why there should be a problem here astounds me - the system was using Microsoft Win 7 drivers, the disk drive is a standard HDD and there were no event log entries about ANY disk errors.
I am not suggesting updated SATA drivers will resolve other Windows 7 freezes but for this particular Vaio laptop model this solution appears to have cracked the problem - the system has been running trouble free with no other change for several days now.