If i am not wrong there are some windows updates which do not allow a computer to be restored back to a date earlier than when they were installed. Just check if thats the case.
Thank you both. One problem I find is that System Restore fails if any registry clean up (such as registry Mechanic) or anti virus/advert removal runs. This is why I weant to remove alll system restore check points apart from the last one.
Essentially, part of what it says is that if you turn off System Sestore, it will delete all existing restore points. It shows you how to turn of System Restore. So turn it off as the article directs, then turn it back on, and create a new restore point. This should provide a reasonable facsimile to what you are trying to do.