Mine does the same thing on occasion. Some days I take it out and it will work fine, the next time I use it I may get a lot of the "Trigger-Screens Together" Error and the next time I use it I may get the Error just upon putting it in Chrono Mode as you are. It is a older XP though. Took it out last week to check some loads and got the same thing so I said the heck with it, packed it up, went straight inside and ordered a CED.
I'll use the main unit as a timer so if anyone needs a spare set of skyscreens and 24" mounting bracket let me know.