In the NS logs, often we'll see a task being "put to sleep" over and over. The log error might read something like this:
In actuality, this is not an error, but is working as designed. However, it might point to another problem if you see the same message repeated every 5 minutes for a task or set of tasks.
When a task is initially scheduled (using either a quick run or a scheduled task), the first thing done is an entry is made into several tables outlining the creation of a new task instance. Then, the task is immediately put to sleep and a tickle request sent to the site server that a new task is available. Only after the task is actually picked up to run will it show as running, or waiting for something. Until then, it's "sleeping" or actually, waiting. Every 5 minutes, the task is re-evaluated, and put back to sleep if there is no status update, until the timeout for the task is reached and it fails.
This message therefore is not actually an error. However, if you see the message repeatedly, then it indicates something is wrong in the pickup for the task, and you should look for errors on the site server or the client as to why it can't get the task.
For instance, if a client is in a Maintenance Window, it will NOT respond to task requests (with a few exceptions) and thus the task will simply remain "asleep" until it expires. Or, if the site server is unable to respond (e.g. the Object Host service is not running, or not at the correct version) it may fail to pick up and forward the task, thus leaving the task "asleep". If the client does not have a requisite agent to run the task, it will remain asleep.
If you see this message, first don't be concerned. It's not an error. If you see the messaage repeatedly for a specific task or tasks, look to the site servers or clients for possible errors, missing agents and/or upgrades, etc. THIS is not an error - find something else.