Overriding GetHashCode()

In this article, Jon Skeet mentioned that he usually uses this kind of algorithm for overriding GetHashCode().

public override int GetHashCode()
{
  unchecked // Overflow is fine, just wrap
  {
    int hash = 17;
    // Suitable nullity checks etc, of course :)
    hash = hash * 23 + Id.GetHashCode();
    return hash;
  }
}

Now, I've tried using this, but Resharper tells me that the method GetHashCode() should be hashing using only read-only fields (it compiles fine, though). What would be a good practice, because right now I can't really have my fields to be read-only?

I tried generating this method by Resharper, here's the result.

public override int GetHashCode()
{
  return base.GetHashCode();
}

This doesn't contribute much, to be honest...