Well could maybe be that he has not downloaded new root updates from Microsoft. I really doubt that Comcast is to blame for that long otherwise other servers would start blocking or bypassing them as unreliable.
No the HOSTS file will not rebuild on it's own, it is a static file that you edit on your own if needed.
Almost certain that it's something on his windows box.
I have scripts to rebuild the default AutoexecNT and ConfigNT if spyware or something else screws it up, but hosts file can contain many entries so just overwriting it is a bad move. You can easily edit it with a simple DOS redirect if needed in a batch file for those that have the folder hidden and can't find it.
I have a script that will do full backup if they have FULL access to the Windows OS.
