Hi, welcome to the forums
You'll find that a lot of manufacturers provide a factory "system restore" which is stored on a seperate partition. The system also gets bundled with software to perform a complete system backup...It's essentially the same thing. Depending on how much software you install or user files you create the "disk" backup could be considerably larger than the factory restore. To use those disks you'd need to run the backup software from within windows.
You'll find that you issue may have been caused by some piece of software the your previously installed which would have made some changes to the registry (how/what software is used to open files). By performaing the "restore" you've not exactly fixed it but put it back to a state where no other software has been installed.
Try to keep a track of any software you install and if issues occur then it's more than likely due to the latest software installed.
Hope this helps