Good afternoon
While trying a Brand New Computer that we've build, I am struggling to use My Vegas 23 Key
I recommend you edit your post and remove your personal information, because this is public user forum.
Your Vegas registration is bound to your Magix customer account. If you enter a different e-mail address than previously, you create a new, empty customer account. The only way to change the e-mail address by yourself is to visit Magix.com and log into your customer account and change the e-mail address in the account settings. Aside from that, the activation should work fine if you enter your old e-mail address in the activation window.