GPU problem/replacement ? For Lightroom and Vegas
Problem solved for Vegas

Solution A


(optional) I have installed thedriver version I wanter (in my case I took the latest drivers,359.00 currently).
CTRL+Shift on Vegas icon, checked clear cache data. (Beware that you may lose some configuration in the process.)
After maybe a few starts (can't tell precisely), it finally works, WITH GPU acceleration.


Solution B
The problem happened again. Solution this time. It might look like a random thing but I've done it multiple times and tested alternatives.

(There was no driver update this time.)


Start Vegas with a blank projet.
Display Preview Window (content should be all black).
Resize preview window (not sure if this is optional, but if it doesn't crash at this point, that's a good sign).
Open the project you initially intended to work with.


Regarding Lightroom: no solution yet.