When the TaskCompatibility.V1 is set (and I would recommend against it as the library will auto downgrade for XP) then you are working with the 15 year old task library and the ITask.SetMaxRunTime method which has proven a bit inconsistent in Vista and later. One of the bugs I've tried to work around may be causing your trouble. Here's the code from the workaround (in Task.cs) so you can see what's happening:
I would strongly recommend not setting the V1 flag and letting the library choose the best version of the native implementation to do the work.
// Due to an issue introduced in Vista, and propagated to Windows 7, setting the// MaxRunTime to INFINITE results in the task only running for 72 hours. For// these operating systems, setting the RunTime to "INFINITE - 1" gets the// desired behavior of allowing an "infinite" run of the task.uint ms = value == TimeSpan.Zero ? InfiniteRunTimeV1 : Convert.ToUInt32(value.TotalMilliseconds); v1Task.SetMaxRunTime(ms); if (value == TimeSpan.Zero && v1Task.GetMaxRunTime() != InfiniteRunTimeV1) v1Task.SetMaxRunTime(InfiniteRunTimeV1 - 1);
