Reboot Coordinator prevents a System Center Configuration Manager 2007 Service Pack 1-based client computer from restarting because it incorrectly concludes that a job is running

System Center Configuration Manager 2007 Service Pack 1 (SP1) will not restart the client computer automatically. It prevents pending important updates from being installed successfully on these computers.
More investigation indicates that the value of the following registry key is greater than 0 on the affected client computers:
HKEY_LOCAL_MACHINE\Software\Microsoft\Sms\Mobile Client\Reboot Management\JobCounter

Microsoft has released a hot fix for that issue.

http://support.microsoft.com/hotfix/KBHotfix.aspx?kbnum=970635&kbln=en-us

To Manually resolve the issue follow this:

1. Stop the SMS Agent Host (CcmExec.exe) service on a System Center Configuration Manager 2007 SP1 client computer.
2. Location the following registry subkey and change its value to 0:
   HKEY_LOCAL_MACHINE\Software\Microsoft\Sms\Mobile Client\Reboot Management\JobCounter
3. Start the SMS Agent Host (ccmExec.exe) service on the client computer.

More details: http://support.microsoft.com/kb/970635