Did you find what was causing that?
I’m experiencing a similar issue on Mac OS X 10.4.7, my DirectoryService.server.log contains a bunch of lines like:
…
2006-09-29 16:15:11 CEST – Network transition occurred.
2006-09-29 16:15:41 CEST – Network transition occurred.
2006-09-29 16:16:11 CEST – Network transition occurred.
2006-09-29 16:16:41 CEST – Network transition occurred.
2006-09-29 16:17:11 CEST – Network transition occurred.
…
I get the message every 30 seconds.
However, I didn’t notice that mach error in DirectoryService.error.log.