I had Plex Server running on and old Windows PC. I just installed it on a new one. When I log in to plex.tv and hit Launch, the web UI opens but can't find the server running on the same machine. When I open the Plex Server and click "Open Plex...}, the web UI opens and asks me to log in. I enter the userid and password I used on plex.tv, and it tells me my credentials are bad.
What do I need to do to get Plex working again?