I'm doing a multivariate linear regression with R, and i find myself with the following residuals vs fitted plot:

![plot][1]


  [1]: https://i.sstatic.net/1azOo.png

As you can see there is a very regular line of points that seems to follow a precise pattern.

**My questions are:**

1. How do I interpret such a behavior, and what can I do to fix it?
2. Is there a way to isolate/extract those points?  I'd like to take a look at them individually in my data set to see if by examining them I notice some patterns in the data.