Hi Mark,
i understand your issue. But please, can you provide some more information about your config and your environment.
Have you checked, that you have permissions to read AD?!
Have you checked the Status of your SCCM Site. Maybe there is an issue with the SCCM itself?!
Please have a look into your other Logs are there any errors? (sitecomp.log, smsexec.log)
You have checked the availability of these logs: ADForestDisc.log, adsysdis.log, etc.
Regards
Eric
Eric Berg -- http://www.ericberg.de -- MCSE: Private Cloud MCSE: Server Infrastructure MCSE: Desktop Infrastructure