With a Personal Edition you are only allowed to work on your own files. To ensure this limitation, your license is compare to the license that created the file you want to open.
If you alter your computer hardware configuration, your license number will most likely change.
To allow you to continue working, Personal Edition allows a limited number of recoveries.
Those recoveries are also used if you open a document created by someone else, because QV won't distinguish between these two cases (file created by someone else or created by yourself, but with a different HW configuration / license number).
Please read the PE FAQ: