Back in 1945, engineers running the Harvard Mark II (an early electromechanical computer at Harvard University) found an actual bug in their hardware - literally, a moth that got stuck in a relay was causing problems. Decades later, we're still finding "bugs" in our computer hardware and software. Wired has an interesting article on their website talking about History’s Worst Software Bugs, including Intel’s Pentium floating point bug which cost them $475 million to repair. Although the article is a few years old, it’s an interesting read.
And the bugs are still continuing today. Just a few months ago, in 2008, Seagate released their 1.5TB Barracuda hard drives with an error that could hang the hard drive during streaming video or low-speed transfers. When they attempted to release a bug fix, they ended up bricking the 500GB Barracudas for other users!
Just remember these “history lessons” before you release your product to market.