After several uninstall/install and few cleaning, the problem was still here.
Mirc 7.46 was able to don't crash 3 or 4 days and crash the next day 6 times in less 24 hours.
It was very boring, I was thinking to abandon Mirc for an other client till I try the previous version 7.45. No problem with the 7.45 on my main computer.
(I'm using a Mirc 7.46 on a second computer without problem)
