One known action leading to the display of this message is if the TriCaster were booted up with a USB drive plugged in. The TriCaster then attempts (and fails) to load the operating system from the USB drive and this is why you would receive the message about the boot device.
To fix this, first go into the BIOS. You can do this by tapping the Delete button during boot up. Go to the Advanced BIOS section and change the Hard Disk Boot Priority. The system hard drive (normally labeled with ST and numbering) should be listed as device number one.
Press the F10 key after changing the boot priority. Select 'Y' to confirm the change when exiting BIOS. Reboot and the TriCaster should launch into the software.