Question: I have a scheduled task on a Windows Server 2000 box which is scheduled to run daily. On Monday, the task ran perfectly in that the thing it fires off (a console application) completed, but the scheduled task itself is still marked as "Running" on the Scheduled Tasks window. So both yesterday and today the job did not fire. 

The underlying process isn't present, the same console application is run by numerous other scheduled tasks with different arguments at other times and they've completed tidily. 

Unfortunately the scheduled tasks log (Scheduled Tasks > Advanced > View Log) doesn't show enough history to show when this job ran. 

When I right click on the task and select End Task it has no effect (the option to Run is disabled). 

I'd like to be able to re-use this scheduled task, but more than that I want to understand what might have caused this issue so as to try to ensure that it doesn't happen again.

Answer: 
When the job terminates, it attempts to update itself indicating (a) the date last run and (b) reset the job status to *blank*. To do this, it must have full control of the job file. If another process attempts to access the job file (most likely culprit being the antivirus software), the job file will be *busy* and will not be updated. 

The best thing to do is to disable the antivirus scanning of c:\windows\tasks.

Hope this is some help.
You could try restarting the windows task scheduler service, but sometimes rebooting a Windows box will solve all your problems ;-)