Hallway conversations are a hassle and waste of much time, at least the ones I'm involved in:
"Hey X, I've been waiting to catch you this morning. The alpha server app is hanging at midnight when we do backups and restart the db. What do you think is the problem?"
"No idea. You'll have to email me the logs and point me at the current source for that app. Then give me an hour and I'll have some suggestions for you. I had some time this morning; you could have emailed me last night when you got alerted and I might have had a fix for you already."
"Well uh, I wanted to discuss it with you in person."
"Not much to go on with just a verbal description - can't help you until later."
(inefficient...happens to me all the time, people who prefer talk over writing an email)