Because computers are complicated animals, too many variables, sometimes it's easier to re-install from clean and never mind what exactly caused it which u may spend ridiculous time finding. If u go to Apple, they are no magicians either, at some point, they will tell you the same thing, restore from scratch. But OK if service free, it just costs u gas.
If I maybe the geek a second: There is a Star Trek episode where Data was infected with an alien virus, they don't know how to fix him. Luckily Data's software has this safeguard where if it detects things has gone haywire, it resets itself and wipes everything and start anew. He lost some recent memory but that's better than broken. That's kind of what needs done for our computers if solution not obvious, and your problem is certainly a weird one.
If I maybe the geek a second: There is a Star Trek episode where Data was infected with an alien virus, they don't know how to fix him. Luckily Data's software has this safeguard where if it detects things has gone haywire, it resets itself and wipes everything and start anew. He lost some recent memory but that's better than broken. That's kind of what needs done for our computers if solution not obvious, and your problem is certainly a weird one.