Actually, you can make a stronger argument that you have an expectation of privacy if you take your computer in for repair. After all, it’s an ethical violation for the repair person to disclose your data or even to examine it himself beyond what’s necessary to accomplish the repair. However, I seem to recall cases where kiddie porn users were turned in by repair techs, and the convictions stuck.
I’ve done computer repairs, and usually we have to copy and paste files so that if something was to happen during the repair, we wouldn’t lose your personal files. If we were to stumble apon child pornography, morally we cannot turn away. Anything else, you would really have to investigate to figure out, and would be an ethics violation in my mind because you are going further then you normally would. Personally if you don’t want your files to be discovered, all computers can have their hard drives removed easily, and just swap a new one in. Reload the operating system only takes 1-2 hours. There is no way to trace back information on a computer if you swap the hard drives, considering all the information is stored there, and all other forms of memory in a computer are temporary, or system bios.
~Shadowjudge~