Meaning of the workflow Event Log?

What is the meaning of the below sharepoint 2007 log?

Log: The previous instance of the timer 开发者_运维知识库job 'Config Refresh', id '{xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx}' for service '{xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx}' is still running, so the current instance will be skipped. Consider increasing the interval between jobs.

---

Means a job is schedule to run, say, every 30 minutes, but when the next one was going to run the previous was still running so it could not start and was skipped.