I had this exact problem 2 days ago. Updating the video drivers fixed it.
Update your drivers.
If that doesn't resolve the issue, what GPU do you have? Windows or Mac?
I have amd radeon hd 6770m 512mb
on imac, osx 10.7.5
I have been to the radeon website, where after much searching it sent me to apple update. I can't find it from apple, either. could be buried, but i'm not great at knowing where to look for these things.
At least 1 GB VRAM is required.
cc_merchant is correct. PPro CC will only let you select a GPU with at least 1GB of VRAM. (Source)
If you used it in CS6 without issue, you might be able to use the GPU hack to get it to work in CC. But that is at your own risk.
aaahaa! ok, thank you. I guess I'll wait until I can upgrade. at least it seems to have full functionality thus far. asante from "one now less puzzled", in Tanzania.