I think, from time to time, Vegas checks in with the mother ship. Looking for updates, perhaps? Checking registration? Passing your recent web visits to the Dept. of Justice?
I asked this question too. As has been pointed out, you can turn it off. I missed the control, although I looked for one a couple times before posting. This is the thread where I asked about it:
Although Vegas doesn't do this (yet), I've noticed that dreamweaver will check around the local net to see if it is already running on another machine. If so then your new instance of it won't run.
Personally, I think this is fair. I'm kind of hoping that the Vegas team will provide a separate batch renderer if they ever do this. It'd be handy to have that running on a separate machine while you keep working in Vegas.
This may not be relevant, but have you checked for viruses lately? Last time I got a computer virus, it tried to dail out at various times depending on what I was doing.