Bug: looping alert window opening a file with an xref and a block with same name

Rhino Rhino for Windows
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1

Hello,
I have a file with an external reference to a dwg, and apparently with a block with the same name. When I open it I have a looping error window
2018-03-27%2009_42_34-Rhinoceros%206%20%20Add%20Instance%20Definition
which I can’t get rid off (as soon as I close it it jumps back).
EDIT: the same happens when I select “update” in the block manager:

2018-03-27%2009_58_55-Block%20Manager
2018-03-27%2009_58_55-Block%20Manager711×525 19.2 KB

We need an option to break the loop, or safely quit (I have to Ctrl -Shift- Esc to kill the process).
Luckilly when I launch Rhino it actually asks me if I want to load the xref, and if I say NO then the file opens.
Version 6 (6.2.18065.11031, 06/03/2018), win10.