I hope you don't mind me dropping in but I have a similar problem. When zooming to 200 or over looking at the shape I'm working on, which has a fractal plasma fill and a transparency, they both get dis-placed so I have to zoom out to either drag the shape slightly or click undo and they both jump back in place so I end up trying to work on the shape at 75 or 100% zoom and when I do this I get the error as occured message. I do have the file I was working on so please see if it happens for you. My product is G.D. 7.1.2.1.8680 CD Oct7 2011.
Stygg
Bookmarks