SQL Server 2005 x64 on Windows Server 2003 x64, with multiple instances (default + 2 named). Engineers moved server to a different domain. Since then, cannot get SQLBrowser to start. Still able to query the default instance, and can access named instances by port (TCP:hostname,port#). When on server, can use SSMS to connect to the instances, all is well from that perspective. No errors in the SQL Server logs.

As SQLBrowser is starting, an entry in EventViewer.Application says that one of the named instances has an invalid configuration, but I haven't been able to figure out what is invalid. Startup continues, and next message says "The SQLBrowser service was unable to establish SQL instance and connectivity discovery." Next, it enables instance and connectivity discovery support; next, another message about that same named instance having an invalid configuration; then an event says that SQLBrowser has started; last, an event shows the SQLBrowser service has shutdown.

I got SQLBrowser to get past the issue with the first named instance by temporarily renaming a registry entry, and now the second named instance can be accessed by name rather than port. Still, cannot access the first named instance by name.

Advice?