Try to uninstall QV again and also make sure that the folders are removed from Program Files. Then remove the registry entries under QlikTech folder. Then restart the system and check the registry again to make sure. And finally reinstall QV and tried to save and re-open the files. I am not sure if this helps but give a try...It worked for me in the past.
Read carefully this document regarding QlikView Personal Edition. You should not be able to open documents you already created even in the same computer as you will see in that document.
Note that QlikView is offering a fully functional software for free, but as any other software, QlikView has its own agreements and EULAs and limitations, to which -of course- you may or may not agree, but please mind your language. If you don't agree, we are open to read and attend your comments as long as they are written in a polite fashion.