SQL Job is already running

Hi

We have a third party app that uses a SQL 2005 backend. There was a problems with the backend server VM and it crashed. The server is running again. However, I've noticed the nightly SQL backup has stopped.

So I've opened SQL 2005, went to SQLServerAgent\Jobs. Then tried to run the backup job that is there. Its failing with the message: "Request to run job FullAppBackup refused because the job is already running from a request from Schedule 1. SQL Server Error 22022"

I rarely use SQL 2005, so I'm not sure what to do next. Probably stop the ongoing request first, as its likely locked. Any adivce on how to proceed?

Thanks