All tasks have a few options in common: Description, Inactive, and Prevent running if already run recently. Everything else varies from one task type to another. Making a task Inactive prevents it from running, but doesn't stop any task groups it's part of from running other tasks. Setting a task's Prevent running... value will keep any task group that it's a part of from running the task too often. In this example, the task "Generate reminders" won't be run more than every 23 hours regardless of how many task groups it's a part of. Once it's been run by any task group, the next won't try to run it until 23 hours have passed.
You can manually execute a task by right-clicking on it. This bypasses any restrictions and runs it for you even if it's not due to be run anytime soon.
This specialized task is for VSys Live, and then only when VSys Live's Apache aspect is running on a Windows machine. It runs the program
htcacheclean.exe in order to clear older entries from Apache's disk cache.