I am using the 12.0.20400.0 SR5 64-bit Edition (x64), personal edition, I was using well, but today I downloaded a demo from official website and opened in my local, then I can not open any of my previous files, it said the file is NOT created by myself, but they are really created by myself in my only laptop!!
I understand your situation, everyone will have 4 chance to open the files developed by other users and if they exceed the count and then they will not be allowed to open the app developed on their own machine.
As you can only open only a limited number of file using the personal edition of Qlikview. TO open and edit more you need to purchase the Qlikview developer license. please use binary load to open the previously created file(open and see the data) from a new qlikview document.