This error is showing up in quite a few forum posts with no definitive solution. I was able to resolve this for a MOSS 2007 small farm running on Windows Server 2008 64-bit. The main symptom is that when you try to open your search settings in the SSP, you get this message in the browser window:
The search service is currently offline. Visit the Services on Server page in SharePoint Central Administration to verify whether the service is enabled. This might also be because an indexer move is in progress.
In my case, looking in the Windows Application log, I had event ID 10036 messages from Gatherer. These messages indicated that the search service account did not have access to stored procedures in two of the databases.
The problem resulted from changing the search service account without adding permissions for the new account to the search and SSP databases. After adding the account permissions in SQL and restarting the osearch service for SharePoint, the search settings in the SSP were available.
During troubleshooting, I also found a set of three event IDs (6398, 6482, 7076) and messages that and Administrative job could not run. That problem was resolved with this hotfix: http://support.microsoft.com/default.aspx/kb/946517.