Pelikal
the HOSTS file is normally used to BLOCK rogue websites, not to connect to them. You can use it to bypass DNS resolution and "hard wire" in IP addresses, but as Mike has already said, thats just heading for a world of pain.
Now the worry is, if you didn't add the Adobe entries to the HOSTS file, who did? Does anyone else have access to the machine? Sounds a bit like someone trying to take the mickey....