Error Message obtained when re-enabling attribute in data model

Does anyone have any idea what the following error is referring to - encountered within the data model on an attribute that I had previously disabled and now wanted to enable it with a slight edit/ tweak?

Can you re-enable the attribute, save and then make the change you want?

Also, can you take a screen shot of the attribute values/settings so we can see what values you are using and trying to save? It could be a special character or something along those lines that is not being caught properly by the data validation.

I have actually noticed that this error came up when I was running queries today as well … I must just think which query it was that I worked on when this came up (sorry things are manic work wise at the moment). I will see if I can remember what it was I was working at the time and if it comes up again with queries, I will be a little more specific as to what the query was that I was running