There has been an on-going issue with using the above listed Planar brand of monitors with ION/EOS/Element. In a nutshell, the Planar monitors will spontaneously go into a mode they call "safe mode" (dark screen and amber power LED). Once the monitor is in safe mode the monitor will not successfully synchronize with the console's video card even after a power cycle of the monitor and/or a reboot of the console. This problem is with the Planar monitor and not the EOS/ION/Element consoles.
The attachment is a FAQ directly from Planar's website laying out the steps necessary to recover the monitor from "safe mode". We have found the following modified version of method #1 to work the best with the three Planar test monitors ETC acquired.
[Modified] Method #1
SEE ATTACHMENT: Planar PL line LCD Monitor Problem and Solutions