Specular light setting switching to specular only randomly

As title says. I will set up my keyframes, pose everything needed and then I have to go through all the frames one at a time to make certain the lights did not randomly switch to 'specular only' all by themselves. Then best part is when I check the frames one at a time and then a previously checked frame decides to switch without any permission from me and it is not discovered until 6 hours later when the render is finished.This is a gmae breaker. It seems like spot light and linear point of lights are the big problems.
Comments
Are the lights animating or static? If they are static you could try selecting them and uisng Edit>Object>Clear Aniamtion>Clear Selected item(s) with the lights selected.
They are animated.Even after clearing them and resetting the keyframes the same issue occurs....random changes to the mode from 'on' to 'specular only'. Moving a light or changing the lights intensity should not cause a light to switch to specular only. Annoying bug that wastes way too much of my time....especially when I have to click through 400 frames 1 at a time and hope that I get lucky enough for the lights not to randomly spitch modes on me.
Try this script - I think it will remove animation from the Ilumination property only, leaving just the starting value. Paste it into the ScriptIDE pane (Window>Panes(Tabs)>ScriptIDE), click the Execute button to run it with a couple of test scene, and if it seems to be working use the File>Save Script As command in the ScriptIDE menus (not the main menu bar) to save it. You can then find it in a content pane, right-click, and select Create Custom Action to put it in the Scripts menu for easy access.
Also, please open a Technical Support ticket to report this as a possible bug
I had exactly the same problem. Thanks Richard the script worked a treat
Richard Haseltine: you are a godsend. HAD the same problem in DS v4.10 & already went through process of manually entering keyframes that would switch the lights back to on, one-by-one, manually! Your script worked marvelously. Tears, man, tears!!