This one happened a couple of months ago, on a Monday morning...
Public Information Officer: "Did the city-wide e-mail go out on Friday? I know I sent it, but I never saw it in my inbox."
Me: "Well..." (checks mail) "I don't see it in mine, either."
Web Manager: (checks mailing list) "It looks like it sent about two hundred, then quit." (checks the e-mail itself) "...Probably because you tried to include a 2 MB image with the text."
Me: "Well, that would explain why our mail server crashed on Friday afternoon, when we were in the middle of setting up for the music festival."
I wish I was making this up. We had to send someone from the festival site back to the server room to do a physical reboot on the server. It was so thoroughly locked that remote control couldn't touch it.