Colorscource spots delayed turning on and off

I have 2 colorscource spots (out of 7) that have started to take anywhere from 1 to 10 minutes to turn on after all the other lights. They will also take about 10 seconds to turn off when I hit the blackout. Just started a few weeks ago and have been in use for about 18 months with no issues. If I remove the dmx and plug in it comes on.Any help is greatly appreciated.