We understand that you are having troubles with the Scheduled Scan that you are setting with your Trend Micro Program. Allow me to share some ideas with you.
The Trend Micro Scheduled scan is designed to be canceled when the following are set on your computer:
An Application is running in full screen You have just ran a scan (quick or full scan or even custom scan) or the program is currently running a scan An update/upgrade is currently on going The system's screensaver is enabled The computer's CPU is currently running high (60% or more)
Make sure that your computer is not on any of the following scenarios when you are expecting the scan to happen.