This happened to me as well, early last week. I ended up re-installing the entire game. Even after that, with no mods installed, it kept locking up. Had to re-boot to get out of the locked screen. Sound was locked up too. The entire game was frozen. So I randomly tried the windowed borderless mode and it hasn't crashed since. Today is the first day I came back to get the modpack and I see that others have had the same problem. So maybe it is not a modpack problem but a WoT problem?