Personal.XLSB not loading with other files

Weird problem. One of the users in my office has a new PC. When she opens Excel by clicking on the icon in the start menu the personal.XLSB file loads no problem. When she opens excel by opening a file, personal.XLSB does not load. I've tried deleting it and replacing it, and it didn't make any difference. Any ideas where I can start looking?

I found a sort-of workaround for it. Creating a new personal.XLSB on the user's computer and then pasting the necessary code in worked, but I can't figure out why. Any thoughts?