If you are use to reading my posts you would know that I am a fan of having very few error warnings in a project file. I was a bit disappointed to see the new 2010 massing tool, is not exactly helping us keep our files clean.
If you create a line slightly off axis in a new mass you will get a report similar to below.
You will have no problem finding the mass with the error from the Mass ID number. Select the mass and go into edit mode. Now try doing a select by ID number on the line. It will select something, but you will never be able to isolate it or find it.
Autodesk have confirmed the problem, and I really hope they fix it. IMHO it is an an over sight by the developers. In the mean time here is Autodesks work around that they came back with. It works, but it is a workaround.
After you find a mass which has a slightly off axis error, apply walls to each face. The slightly off axis message will transfer to the wall applied to the slightly off axis mass face. When the error appears that is the face with the error. Now you just have fix it.
I do like the new massing tools, but it still needs work.