I was doing testing with the card (taking disk images on Linux) and had the write protect on to ensure the card was not corrupted. I forgot to unlock it after that. Simple thing, but it took me a minute to find out that was the problem. I thought I had corrupted it.
Who am I? What have I programmed? Right now, I'm working on Pocket PC software. It's not ready yet, but it's coming along nicely. Before, I worked on software for genetic analysis, and before that, for business analysis. My main interest is machine learning and AI. I'd say I've done useful things; at one point, I was on a patent application for distinguishing types of leukemia using neural networks.
But it shouldn't matter what type of software you are working on. The principles of UI (not just GUI) are well founded, and have been for at least ten years. Any application should at least try to obey the important principles.