trust issues

I'm still really pissed about something that happened with one of my colleagues. I wish I could beat him up, but I can't.

I was training him on my software, and he had the wrong version on his laptop. Since there is limited backwards compatibility, I had him work on an assignment on my computer. He started the assignment and I went outside to smoke a cigarette.

Ten minutes later I came back. The whole time I was smoking I had an uneasy feeling about leaving him on my computer unattended. But, I tend to trust people. I let some kid I barely knew live in my house for free. I let another kid I didn't know stay in my house while I was on vacation with my dad (he was a student in Denver for the DNC). I've only had a few problems. I want to trust people.

Anyway, I told him that I would give him a copy of the new software version so he could work on his own machine. He handed me a USB drive. Normally I just click on the file to be copied and say send it to the USB drive because I don't get into people's personal stuff, and wouldn't look at files on a USB drive. But this time I had to because there wasn't enough room on the USB drive for the software. I asked my colleague what I should do and he told me to delete the recycle bin.

Just out of habit I opened the recycle bin to make sure I wasn't permanently deleting files the customer gave to my colleague that I didn't have a copy of. Imagine my surprise when I found a bunch of MY files from a folder on my computer called "personal". The files included bank statements I had downloaded for my taxes as well as my W-2.

I was like I don't fucking believe this. I wiped out everything on the USB and copied the software. Then my colleague started talking about how he encrypts everything on his computer so no one can steal it. I thought that was strange. I made a comment about people stealing files and how it sucks that you can't trust anyone. I really wanted to confront him and then punch him in the face. The circumstances, not worth explaining here, prevented that.

Now I wonder what I should have done. How could someone do that, and worse, how could a supposed colleague of mine do that?

Some people really, really suck.