This co-worker is actually very smart, but her brief brainfart today gave me a giggle. Everyone has moments of dumbness when technology is around...
Her: Can you help me out? The printer won't print my A3 document.
Me: Is there an error or anything?
Her: Nope, no error, it just isn't printing.
Me: Weird... not out of paper?
Her: No, I refilled the tray just in case.
Me: *looking it over* Hrm, nothing in the print queue, no errors...
Her: *sigh* This printer just hates me.
Me: Um, I hate to ask... did you send it to this printer?
Me: Did you send it to #8 or #9?
Me: *trying not to smile* This is #8 - #9 is the identical machine down the other end of the building.
Ironically, I had made the same mistake the previous day, sending out an all-staff email that #9 was not working pending a repair tech visiting and asking them not to send print jobs to it... when #8 was the one that was broken down.