Is the following normal and acceptable and, if not, how should I address it?
I started working at this new place a few months ago. I am on a desktop. At first, I noticed things like my computer running when I had turned it off the prior night. If I leave my coffee cup in front of my keyboard, it is moved aside in the morning. When I mentioned needing admin access on my machine, my ranking co-worker (defacto IT guy) admitted that he entered my office and did it the night before, after I had left. I have notice this now, I would say, 6 or more times. Before assigning me this computer, they had not wiped it. I know there are other user accounts on my machine. It generally feels like a lack of trust and professionalism. The office doors are key locked, at night too.
Am I right to be irritated that people are regularly going through my office without asking? I recognize that it is all company property, but I find it a bit rude.
EDIT: It sounds as though I am probably in the wrong to feel defensive about this. I never keep personal information of any kind on my work computer, but I come from a company with very different practices. Before, I had a laptop that was required to be taken home, the rule was to never let it leave your side unsecured. IT changes were pushed remotely. This is just new and uncomfortable, but not wrong.