I faced this issue when I try to deploy a solution and it failed. I then started the service and redeploy the solution; however I face the above issue. To fix it, you need to cancel the current deployment then redeploy the solution.

Solution for SP 2007

To fix it, you need to cancel the current solution deployment. Go to Central administration -> Operations -> Solution Management and then cancel the deployment. Next, you can redeployment your solution.

Solution for SP 2010

To fix it, you need to cancel the current solution deployment. Go to Central Administration -> System Settings -> Manage farm solutions and then cancel the deployment. Next, you can redeployment your solution.