So when you restart the async service in services, does it stop again? Or does it show it is running? My guess is it stops.
Check the login for the account running the async service to make sure the password hasn't expired. Or that it hasn't been removed as a local admin on the machine (it needs at least performance monitor users I believe). If the password expired,
you will need to reset it and then change the password for the logon account in the async service.
Open the deployment manager, click on servers and make sure that you see full server for the CRM server if everything is on one box. I had a strange case where the customer stood his ground and said that it was a full server and there were no changes,
but when looking at the deployment manager, he only had the front end installed. No back end means no system jobs run. My guess on that one is that someone restored an old backup and didn't claim responsibility for the task.
Check the event logs on the CRM server to see what they indicate. You may also want to run a platform trace if your not getting anything from the event logs.
Jason Peterson