"Access invalid attribute" Alert

[Alexandre Enkerli]

Been getting this once in a while. Navigating an OO document using 
arrows (while in edit mode), this alert will pop up:
"Alert
Access invalid attribute location 25 (length 19)"
With an ok button.

It doesn't seem to affect anything (it's just an alert) and I can't 
specifically reproduce it, but I wonder what causes it. It's mildly 
annoying because it interrupts the flow of navigation.
It's not localized (i.e., same message in French loc).