Microsoft Office SharePoint Server 2007
SQL Server 2008
Out of nowhere, we found that indexes were not getting propagated to our Query server.
Within ULS logs, we would see messages like "Query Server(s) not ready".
Within Central Admin, we would see messages like "Waiting on Initialization (XXX) (on Search Admin screen) and "Propagating to Query Server" (on Search Status screen).
Search propagation would be stuck in this state for ever.
No amount of restarting or recreating SSP would solve the issue.
Turns out that “Windows SharePoint Administration Service” was not started on Query server. Once re-started indexes started getting propagated to the Query server.