I recently worded on an issue where you would import computers into an imaging collection and it would take hours before they would kick off to image. I found a Microsoft Hotfix to fix this issue. Microsoft hotfixKB980270 took care of this issue for me I applied the patch rebooted the server and everything we imported starting imaging. This issue focus on System Center Configuration Manager 2007 Service Pack 2 AKA SCCM 2007 SP2 but I can tell you from experience SP1 also had the same issue and there was a separate hotfix to fix that issue.
Computer Associations Problem SCCM 2007
