Hi there, @MarkFulton. 

I'm here to help you get past this issue. When QuickBooks crashes while sending invoices could be a browser-related issue. 

It could be that the stored cache and site data in your system are the reason why you're unable to send an invoice. We can perform some basic troubleshooting steps to fix this issue.

Let's open a private window and use it to access QBO. You can press Ctrl + Shift + N for Google Chrome or Ctrl + Shift + P for Mozilla Firefox and Internet Explorer. Once done, let's send an invoice again and see if it works. If it did, go back to your regular browser and clear the cache to eliminate the junk files.

If you still encounter the same issue, we can use other supported browsers. 

I'll be always around here to help if you need additional assistance in sending your invoices with QBSE.