Sophie Vuille 

I do wonder, given the problem is isolated to Alignment -  if its the TM or the files causing the issue.

Is the TM being referenced for alignment working error free with a different translation project?

Does Alignment crash regardless which files you pickup, or does it freeze Studio when picking up specific files?
If you feel it's a specific file pair then, can you take your source / target files - and create individual single projects in Studio?
This way I am hoping we can identify which file is problematic and then follow this article to try repair your files: https://gateway.sdl.com/apex/communityknowledge?articleName=000001410

If you feel alignment causes Studio to freeze under all circumstances, then please try repair Studio using this article for guidance: https://gateway.sdl.com/apex/communityknowledge?articleName=000001414 

I hope this helps

Lyds