AutoCAD have added another new feature to their software in 2013. One of the guys in the office came to me and asked,
“Why do I have a load of exclamation marks all over my drawing?”
This was because for some reason the associativity of his dimensions had been lost. (Bulk re-associating seems to be impossible but I will look into that).
The new feature highlights the problem so you can fix it. If you don’t want to see this you can set ANNOMONITOR to 0. Then the feature will be off. This works in AutoCAD LT too.