Howdy
Possibly Windows or another program auto updated and broke Vegas? I would check to see what has been installed on your PC about the same time Vegas wouldn’t function properly. It could be anything like a Codec update or your gpu driver update. If you are using your gpu in Vegas try disabling it to use the cpu instead as I sometimes have issues with that. If all that fails try installing it to a different HD? Try running Vegas in Windows Safe Mode (if it can) as maybe there is a driver conflict? Seems like it’s a Windows issue vs Vegas so check what Windows has updated and go back (Restore?). Check in Windows Event Log to see if there are any details re: Vegas at the time the event happens. Could de the SSD has an issue?
Good luck