Hi Jean,
this is a long-time bug we've been facing. The good news is, we
think we fixed it a few days ago.
Could you please download and install our latest nightly build and
see if the problem persists. That page also has sig and SHA1 to
verify the download.
All the best, steve
Disclaimer: This is a development version which has not been
thoroughly tested yet - bugs or crashes are to be expected. Thanks
for helping us test.