Also, not emptying the recycle bin. I can has storage? No u can not has storage, because your deleted files haven't actually been freaking deleted yet!
Edit: And when people don't close programs they aren't using. "My computer is running slow" - "how many browsers do you have open?" - "36, why?".
Haha, I'm awful at both of these, although I don't complain to anyone when I realise it. I'll wonder why a game is slow when I have 4 other games, 800 tabs and Photoshop open already.
I also never remember to empty the recycle bin, as I usually do shift+del to get rid of a file, so usually don't have to empty it.
Chrome has given me the bad habit of often just typing "facebook" into the address bar and hitting enter, which is essentially the same as searching for it and hitting "I feel lucky". It's not so bad, except I only use Chrome on my work laptop, on my PC I use Firefox which isn't so good at handling it.
What annoys me is people who use the mouse to do everything, it's so slow. I just want to reach over and take the keyboard from them so I can navigate around faster for them!
Slow typing annoys me too, all my family can touch type except my dad, even my 9 year old brother. Watching my dad trying to type an email or something on his laptop is painful as he jabs away with two fingers then stops while he tries to find the next letter. Interestingly my brother's school does some on-line touch typing flash game exercises during their IT lessons, it keeps accuracy and score ratings for each pupil over time, it's a great idea.
The biggest thing that annoys me about being 'The computer guy'? It has to be people assuming I will fix their stuff for them, or anything vaguely electrical. I have no issues with a mate bringing his laptop around to have a quick look at it, but yesterday I had my friend's cousin's partner sending my friend a text message saying "Can you ask Chris to do my Uni project website for me? I need it up and running by Jan 9th." I've never even met his cousin, let alone his partner!
Another thing that bugs me, although this probably makes me sound incredibly arrogant, is when people ask my advice then don't take it. When they inevitably make a hash of whatever they're trying to do I'm then the one they call on to sort it out for them, which usually ends up with them doing what I recommended in the first place!