I have the same problem on three different Mac's. I am not using Open GL or any ATI boards so the problem lurks somewhere else. I have found the program to be so unstable in some states that I am still using RD Studio 5.5 all the time. I've allocated at least 100 MB of memory, 300 MHz & 400 MHz G-3's plus a 400 MHz Powerbook. All running OS 9 and all have the same problem. For the record it was happening w/ OS 8.6 too before I upgraded.