Time and Chaos has a feature to monitor your appointments and popup a reminder screen. The really cool thing is that it is a separate process that can run by itself whether or not Time and Chaos is currently open.
Within Time and Chaos, click on Tools and Options and go to the Calendar section. There, you can enable the alarm utility. For instance, if the text reads currently as Disabled, click that button to Enable it.
Once enabled, a small Time and Chaos icon will appear on your system tray (by the clock on your taskbar of windows). Right mouse click this icon and you can choose the option to Start With Windows so the alarm monitor starts automatically the next time you reboot.
Ensure that within this right click menu, that both Enabled and Start With Windows are checked.
This help article applies to Time & Chaos 7