Solved Latest Video Pro Software

As far as GPU acceleration of video processing is concerned, I have 2 choices: Intel HD or Advanced Micro Devices

Make sure to set GPU = AMD or Off

AMD Graphics Cards normally work well with Vegas.
In one of the latest build updates for Vegas Pro 15, you should now have an option to render video using AMD graphics VCE mode.

Since you are using AMD Graphics, check that you have installed the latest Driver for AMD Radeon graphics.

The problem with some Intel and AMD CPUs was caused by Intel and AMD, not Microsoft.
Intel was affected more deeply by this security flaw than AMD CPUs.
However the security patch for Intel and AMD CPUs had to be applied via Windows.
www.theverge.com/2018/1/3/16846784/microsoft-processor-bug-windows-10-fix

From what you have reported though, it seems like the Hardware you installed has caused the problem.
It may have screwed something up in the Windows Registry, which is also affecting Vegas.
I think this is exactly what happened to my own computer when Vegas stopped working and I was forced to do a Clean Install of Windows.

Thanks for your message. You say that in one of the latest updates for Vegas Pro 15, I should now have an option to render video using AMD graphics VCE mode.
Well, I don't see this in my system. Where do I find such Upgrades within Vegas?
I am going to have a person helping me with updates to the Motherboard (Gigabyte) and we will also look at installing the latest Driver of AMD Radeon graphics.

Thanks for your efforts and screen shots. Found the source of all my problems! Turns out that my Video clips Hard Drive had become corrupted - so badly that it was impossible to play any clips smoothly. Purchased a new HD this afternoon - fitted it - played some sample clips. Now runs like a dream. Did an update to AMD Graphics as well.
Thanks guys for all the help (You and Derek)