I am running blender 2.49b on my MAC OS X 10.5.8. I downloaded it from Blender.org and it worked fine until suddenly it started having problems. When I open blender a pink rectangle appears on screen and then blender quits and I get the error message “Blender quit unexpectedly”. I have no idea what caused this and I am wondering if anyone knows how to fix this or if they have had this problem themselves. I have other versions of blender that work properly so I don’t think that it is my computer causing this.
Here’s a quick fix: install Windows 
In all seriousness though, have you tried re downloading the installation? Also, are there any driver updates for your specific video card? I’m not sure how drivers work for Mac so I can’t say this will work for sure but that’s what it sounds like is causing the issue.