This is a Windows system installed file with Windows File Protection (WFP) enabled.
mstask.dll has 36 known versions, the most recent one is 5.2.3790.3959 (srv03_sp2_rtm.070216-1710). The average file size is about 288.54 KB.
A Task Scheduler engine performs the actions scheduled through the Task Scheduler. A Task Scheduler engine communicates with the Task Scheduler service to execute tasks. The service creates a task engine to run tasks.
(Note, the behaviors below are for all versions of mstask.dll, select a unique version for details.)
Located in the registry at 'SOFTWARE\Microsoft\Windows\CurrentVersion\Shell Extensions\Approved'
United States installs about 47.27% of Task Scheduler interface DLL.