Screen Flicker

Anyone else been getting the most horrendous screen flickers and consequent slow downs, freeze ups and application crashes when programming with either GLSL or OpenCL under 10.6.x ?

[ Just in case you wondered, I have and was beginning to seriously wonder about taking the machine back to the vendor as it is under warranty, due to a serious spate of such screen flickering resulting, in one instance, a keyboard that now won't be recognized by any of my previously compatible Macs :-( ]

Even something as relatively straight forward as GLSL-SphereMorph.qtz can cause such screen flickering problems that just can't be found, as such , under Leopard 10.5.x