My application failed to start via "Task Scheduler".
The error in "Event Viewer" is: System.IO.DirectoryNotFoundException
The "Task Scheduler" tries to run this application with the "SYSTEM" user. The problem was that a "network drive" was not mapped for the "SYSTEM" user. So what I did was, I created a ".bat" file and mapped the "network drive" before starting the application:
net use T: \\172.20.2.215\images
cd C:\MyApplication
start MyApplication.exe
So check your logs first: "Event Viewer" -> Windows Logs -> Application