We have had a couple of instances where a task did not complete, and was left running indefinitely (days and weeks.)

Looking at the log for one of them, I found these lines:
Task (4958) was added to processlist
Task started:

Comparing to what is in the log when a task behaves normally, it doesn't have the process status lines normally found:

Process status - About to SendTaskProcess (4773)
Process status - About to RemoveTaskProcess (4773)
Task (4773) was removed from processlist

To get the job/task to stop running, I ended up cloning the job, and deleting the job that was hung - it wouldn't stop when I tried to stop the job, or inact/act (I didn't try restarting the server, since I didn't want to affect any other jobs.)

However, I notice now when I look at active processes on the server from the main menu, the task is still there and shows that it's still running - it's no longer associated with a job. Will this require reinstalling VisualCron to clear up? If so, will this cause any problems in the meantime?

I didn't have timeouts on any jobs; I plan to add a timeout - will this be sufficient to prevent the problem from occuring in the future?

I had this once. What I did was stopping and starting the service in the service window (manage server screen). This helped me out, but is was strange that it happened. Don't know when this happened in the past or whith what version, but I do remenber that it did.

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It depends what kind of Task it is. There are a lot of things that can happen when you run background Tasks. For example, some applications may generate an popup Window that requires user interaction.

As you say, a Timeout is the best way to prevent long running Tasks..

As Erik mention, you can reset the state by stopping and starting the VisualCron service.

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