When building your own wheels -- or anything -- ensuring you have quality parts is paramount. I've built many wheels now and usually use DT Swiss spokes, but for my custom trike project, the spoke vendor wasn't known. And it had disastrous results.
Last year my recumbent trike (link in progress) developed a case of Spokus Brokenus on one of its front wheels. It's a "tadpole" trike, which means there is one wheel in back for propulsion, and the two in front steer. It was odd that just the one front wheel had this issue, but it became clear why.
One of our builds was breaking recently, and the error messages reported from Xcode 3.0's xcodebuild command were unusual. Xcode 3.0 has broken dependency handling, at least in one case.
Recently at work I encountered a problem with dylibs (shared libraries) with our OS X application. Our application is based on a cross-platform modular framework that runs on four different platforms, and the modular plugin architecture makes it easy to include new features into our programs.