I looked around in the Vegas Forum and found this by Stephen Mann:
“Things to try:
If your PC is overclocked – don’t!. You are just asking for instability.
Turn off GPU support. First in the Preferences tab and again in ‘Render As/Customize Template’. If you have a fast processor, like a high-end i7, then GPU support may be counter-productive.
Disable the Antivirus software.
Set the User Account Control (UAC) to “Never Notify”. (Control Panel, Action Center, Change User Account Control settings). UAC can sometimes interfere with program execution if the program or Windows components used by the program are installed by a non-admin user.”
I did all this stuff and now my renders are smooth.
Thanks Stephen and everyone else on this forum who pulls my fat out of the fire!
-Robert