Unknown Microsoft Network Domains

Hi,

There is something weird with our network, all of the sudden there are an additional 7 domains in our network, none of which are accessible. So when I double click on “My network places/Entire Network/Microsoft Windows Network” in there I will see 7 other domain that shouldn’t be there. How do I delete or get rid of these?

How can I find out if we’re being hacked or if this is a case a hack? Thanks!