It's just what the error says. You can't have that particular debugging switch active when optimizing for speed. Under your project settings, the general tab in C/C++, you can change Debug Information Format to disabled.

Thanks

Check your compiler optimisation switches in project properties or something (I havn't used VC++ ide ever but I guess they're in there somewhere)

If you look here:
http://msdn2.microsoft.com/en-us/library/fwkeyyhe.aspx

You will see that command line switch /ZI means include debugging symbols

/O2 means compile 'fast' code

They are obviously mutualy exclusive you can't compile lots of debug code in AND have fast code!