You remember all the fuss over the Y2K (Year 2000) bug where the world was supposed to end because computers wouldn't be able to handle the change in year because all the programs were written with only a two number date format so a computer thought the 00 after 1999 was 1900 not 2000? Well, it may not have caused problems but NASA are so worried about the software on the space shuttle not handling the change of a year (i.e. from 31st December to 1st January) they make sure they're not in space at the time (via Kottke).
The worry is that shuttle computers aren't designed to make the change from the 365th day of the old year to the first day of the new year while in flight. NASA has never had a shuttle in space December 31 or January 1.
"We've just never had the computers up and going when we've transitioned from one year to another," said Discovery astronaut Joan Higginbotham. "We're not really sure how they're going to operate."
So one of the world's most advanced organisations can't vouch that the software that runs one of if not the most advanced device on Earth won't flip out when the year changes. Have they not just tried leaving one on while on the ground?