Hate that bug, though are you certain it's caused only when opening chests/furnaces? I believe it's happened to me occasionally out of the blue, and though minor and easily corrected it still is a big annoyance.
Quote from BabyCreeper »
How is that annoying?
It's as annoying as the coloured text you've seemingly abandoned, finally, after causing quite a lot of eyesore on these forums.
Issue with this is that it's not a minecraft bug, but one inherent to (at least) windows. I've had the exact same thing occur in just about every game I've played. If you hit two keys at very similar times sometimes the system doesn't update them as being released properly.
I actually got pretty good at getting it to goof up my forward key in WoW by jumping right as I let go of the W key, just because it was so frequent.