When someone is dealing with a hardship and you say "I'm sorry" only to have them reply back with "Well, it's not your fault."
I see what you mean but on a related note, I hate when someone you know dies and people say 'I'm sorry'. I mean, did you murder that person? No? Then what on earth are you saying sorry for? But then there's no acceptable alternative either so I see your point.
Update.
I also despise:
Dripping taps. Actually lets make this, I hate any needlessly repetitive noise. Because once you hear it you can't tune it out and it tortures you for the rest of eternity.
People who talk loud on the phone. I concur with Az on this one, oh em gee, please be quiet people, the phone was invented so you
don't have to yell to be heard.
People who interrupt you when you're talking. Okay maybe this isn't mundane and normal, more like extremely rude and bad mannered. But either way, SHUT UP AND WAIT YOUR TURN.
When someone swallows loudly. I hate the noise it makes, it's gross. I know it can't be helped but that just makes it even worse, it's the snoring thing all over again.
Mess. Now don't get me wrong, I'm not a clean freak nor am I super tidy. But I hate there just being **** everywhere. Some people just seem to be inherently messy and I can't understand why. Doesn't it drive them nuts? I feel like my brain is on fire until someone has tidied up.
I also agree with the above thing about doors being only halfway open or shut. If it's just hanging there, it creeps me out. Have it open OR shut people!
When people don't adhere to the queue. Maybe this is just a British thing, but ahem....
WHAT THE HECK DYA THINK YA DOING PUSHIN IN FRONT O ME? SLING YER 'OOK!!!