What is it?
MS Task scheduler - mstask.exe

What does it do?
mstask.exe - Gives you the ability to schedule tasks to be run at certain on certain days and times. I use it to automate as many tasks as I possibly can.

Virus Precaution:
When googling I was able to find

W32/Opaserv -H
W32.Myparty@mm

The mstask.exe which is from Microsoft is located at c:windowsSystem32mstask.exe . If you find it anywhere else then you should be suspicious for sure.