OK, to have a go at stopping the crashing, first look at the memory settings for the Studio. Talend have this set far too low for most people's requirements. Go to a file called something like (something like because in different versions it changes slightly) "Talend-Studio-win-x86_64.ini". It will match the name of the executable you use to start Talend. Check the contents of this file. Mine says....
-vmargs
-Xms512m
-Xmx8192m
-Dfile.encoding=UTF-8
-Djava.net.preferIPv4Stack=true
You want to up your -Xmx value as high as you can afford. I'm using 8GB here. A lot of data processing is handled in memory so it makes sense to have a lot.
Hopefully that will go some way to solving your crashing (but I don't use the DQ tool, so there is no guarantee sorting the memory will do it).
Now with the workspace in use issue, this could be caused by the fact that Talend is crashing before clearing the workspace lock file. You can do this manually by going to the .metadata folder inside your workspace and deleting the .lock file.