I've spent 10 hours over the last two days debugging a SAS program I wrote about 2 months ago. It was written for a paper that's coming along nicely, but I haven't revisited the data (or the program) for a while.
Unfortunately, I didn't document the program very well.
I thought, "well, all I have to do is run this one test. That shouldn't take long."
Cue Jaws theme song and commence profanity
When will I learn?
Now that I've gotten down to a part of the program that has to run for a while (merging two VERY large (> 50 gig) datasets), I can take a break.
update: It finally finished running. It "only" took 14 hours (yes, that's right, 14 hours). And that's after having used every trick I knew to make it more efficient.