Dynamic lighting moves one square to the left

I've had this problem before on this particular game - Forge of Fury - which is a bought dungeon.

What happens is that periodically I come to move my characters to a dungeon and discover that the Dynamic Lighting has moved one square to the left. (See the picture of the Dynamic Lighting layer below). This section (the Foundry) is the second time this has happened on this dungeon. Putting it right takes quite a considerable amount of time and effort, with no guarantee that it won't happen again.

What causes this and how can I prevent it, please?

I don't like to bump this, but does anyone have a clue why this happens?

It looks like either the Map layer or the Dynamic Lighting layer has moved. Beyond accidental movement by the GM, I'm not sure what could cause it.

The easiest fix would probably be to go to the DL layer, hit CTRL-A to select all, then push the right arrow on the keyboard.

Edit - on second thoughts... what are the white dots? Are they on the Token layer? If they are, it looks like it was the Map layer that got moved. In that case, do the same fix but on the Map layer and push the left arrow.

The white dots are on the token layer, I think. They seem to have lighting instructions attached. 

I hadn't thought of the map layer having moved, but Ctrl-A would make it so much quicker to move the map back. Thanks for that, I hadn't known about it for this - I use it when using Word, but hadn't thought of it in this context.

No problem! I kind of wish there was a way to disable keyboard shortcuts to the Map layer, myself. It's not somewhere you generally need to get in a hurry, and if you accidentally move to it, a single click is almost always going to select the entire background map.