I'm not using anything special, just the standard Apple mouse with no special software or drivers. But like I said, the build that you reported as not working did disable acceleration as per the docs from Apple, the ioquake code, and any other sources that I could find on the subject. So that pretty much leaves just two possibilities: 1) accel simply isn't the main cause of the problem, or 2) the code fix just didn't work for you for some reason (perhaps a safety check failed or something). You reported that it possibly made things worse though, so if that's the case then the previous fix must have worked code wise, it just didn't produce the desired results.