Sadly, while the theory that you can add several volatile chemicals into a pot and you could create a pandemic is true, the chances of it happening are slim. Even if given an indefinite peiod of time.
The chance that the programs from the internet may come together and fit together like pieces in a puzzle and create an artificially intelligent virus is slimmer than that. More likely, the super-virus will attempt to form, but more than one of the programs is going to conflict with each other, and not provide the virus with what it needs, resulting in it's downfall or the creation of an incredibly inept, yet powerful virus. "Inept", as in, reveal itself to every computer on the planet, so it can be crushed by Bill Gates.
