I'm glad I found this thread. I was having a similar issue. Starting a brand new file in Illustrator with GPU Preview enabled but then placing a jpeg I created in Photoshop caused the document to switch to CPU Preview (GPU greyed out). Reinstalled version 25.0 and it is fine.
I thought the issue was my monitor and/or my pantone swatches. I spent so much time adjusting the colours in my files before realizing it was the preview mode that was messed up. Frustrating!
I'm glad I found this thread. I was having a similar issue. Starting a brand new file in Illustrator with GPU Preview enabled but then placing a jpeg I created in Photoshop caused the document to switch to CPU Preview (GPU greyed out). Reinstalled version 25.0 and it is fine.
I thought the issue was my monitor and/or my pantone swatches. I spent so much time adjusting the colours in my files before realizing it was the preview mode that was messed up. Frustrating!