Hi, I'm working on the Mac 10.5 platform with gcc: --versioni686-apple-darwin9-gcc-4.0.1 (GCC) 4.0.1 (Apple Inc. build 5493) Using XCode to compile my works fine in Development mode, but when I switch to Deployment I start getting these non-virtual thunk errors. I've set up a stack overflow question that details the issue: http://stackoverflow.com/questions/2544152/mac-gcc-non-virtual-thunk-error But so far no one has been able to suggest anything useful to try and solve the error. As far as I can tell the options between the Developement and Deployment modes in XCode are as similar as I can get them. So I'm out of options to tweak. Whats the root cause of this error? And why does it compile/run in Developement? Because if there was an issue in the code itself wouldn't it break in both modes? Sincerely -- Matthew Allen