We have had some reports from users having a problem with ArtRage 2.5 crashing when launched on OSX. So far this appears to be happening on OSX 10.4.10.
We're working with these users currently to fix the problem and as soon as we have the solution we'll put out an updated version. In the meantime, if you are experiencing the problem please send a copy of the crash report generated when the application crashes to firstname.lastname@example.org, with your OS version and Quicktime version, and we can use that information to help track it down faster.
Sorry for the problem!