You can read something on the screen a dozen times, but don't spot the typos until you have a printed hard copy in front of your eyes?
Not such a big deal when it's a simple sheet of letter paper. Slightly more annoying with it's a 2 x 1.25 m colour poster for the conference I'm going to this weekend. I spotted one typo literally as it was coming off the printer roll. I thought, "I'm not going to reprint it for one lousy typo. If there's a scientific error, or two other typos, I'll reprint it." And while showing it to my student Michael, I found one more and he found one more. Dang! Back to the printer once more tomorrow, hopefully for the last time.
I'm also hoping to get the paperwork finished on my latest grant before I leave this Saturday. The deadline for submission is Tuesday -- while I'm out of town. Which is just a touch nerve wracking. But I was assured by the people responsible for such things that they would have the paperwork done by tomorrow. Fingers crossed.