DaraGrid breaks when item property inside has been changed

[Myszax]

When Conversation object has been changed inside DataGrid_Upper or DataGrid_Lower item selection is broken.
For example when I click Inspected on DataGrid then I cannot select other item/play sound of other item.
Everything back to normal when I uncheck box and revert the state of this item.
Same applies when I edit text of some item.

[Myszax]

I have found that public override int GetHashCode() in Conversation causing this problem or rather implementation IEquatable.
To be more precise GetHashCode() shouldn't be implemented on mutable (editable) fields/properties.