Windows 7, Server 2008r2 and Server 2012 network switching to public

How many end users or techs have had issues with their PCs and workgroup servers suddenly jumping from home/work to public, blocking access to data, printers, apps, etc?  Often times, this is caused by a router change (which if you are an AT&T U-verse subscriber, could be once every few months).

But in many other instances, this phenomena occurs without warning and for no obvious reason. What’s even more interesting is in an environment of, say, 8 computers, 5 might change to public while the other 3 remain set to private business.

I write this with no solution offered, merely the observation that this problem seems to be fairly frequent and I’ve only really seen it in the last year or so; and never saw it years ago on Windows 7.  Have Windows updates caused this to be more common?  Are hack attempts through the network responsible?

The security policy can be manually set on a single machine to cause it to default to a private network, but I’m more interested in what has been causing this more frequently than before.  I probably get a few calls per week that are directly related to the public network jump on peer-to-peer networks.

I’d love to hear feedback from others in IT that have also experienced an increase in this issue.