I think I know what happened there One of the libraries used by Welcome/Boutique was updated and exposed some "bad" code within these programs, so they ended up crashing.
That was fixed, and 17.04 users should add the Welcome "Updates" PPA to get the absolute latest version -- if anyone is to run into that, see here:
Side suggestion -- if discs are causing bother, how about imaging a USB stick?
One of the libraries used by Welcome/Boutique was updated and exposed some "bad" code within these programs, so they ended up crashing.