Happens to all of us. Even if the mule system in original d2 ladder works 100% of the time .. i even managed to wait long enough for it to crash because of cooldown, minimizing the game and chatting/cooking etc... thinking 5 minutes, but waiting just too long and bam, items lost... luckily never lost something truly valuable from it, but of course some items is always hard to lose.
We all make mistakes. I suspect also those that always brag about being "good" at d2, and hardcore, lol .. they lose characters all the time.... when rushing too fast, you're going to die sooner or later. It's easy calculations.