mauro,
...Dariusz, not understood what you're asking me to do: having both FF and TB installed and then what action...?
OK, in your original post you stated:
...recently discovered that now the email client of Seamonkey -assuming same as Thunderbird-, cause a system trap when calling the "email client" window from Seamonkey (no problem if I start a new message compose)...
I interpret that to mean:
1) you are in web page (browsing) where there is an email link
2) you click on that link and expect that the email client window would pop up, thus allowing you to create an email
3) instead of this outcome you experience a trap/failure
Is that correct?
Subsequently in your post I was responding to you stated:
...I have installed Thunderbird 45.8 pentium4 to see what happens...
...and I was commenting on the fact that I have FF & TB here, which have been pretty solid for me, so I could certainly try to reproduce your scenario, and if I fail to, we could try to chase the DLLs down given that I am on CP2 release as opposed to AOS install.