Suddenly, all my legacy XP clients and 2003 member servers won't connect to the 2012 r2 server I installed 3 weeks prior. The error simply says, "Windows cannot find <2012server>". Note that I can ping just fine and DNS appears to be working OK. They connect just fine to the 2008 server and all other network shares & resources.
2 DCs (a 2008 and the newly added 2012)
20 Windows 7 workstations (unaffected)
3 legacy 2003 member servers*
6 legacy XP workstations*
Forest Level raised 3 weeks ago from 2003 to 2008
* Unable to find the 2012 DC on the single network we have after 3 weeks of doing fine.
Thanks for any direction.