Computer Repairs

I get a lot of questions from friends and family on how to fix various computer-related issues. Today my father wrote me about another computer-related issue:

"This computer is acting crazy today--when I walk in front of it to sit down it shuts off--without me touching anything. Any ideas on that one? Maybe I'm radioactive or something."

After a quick laugh, I sat down to figure out what might have caused it. I thought maybe the power cord was loose and he bumped into it when he sat down, knocking out the power. I asked if it happened more than once, and he said that it had happened four or five times already today.

I drew a blank. I told him that I didn't really know what to say, but then he said that he eventually came up with a solution on his own. Now, when he wants to use it, he "sneaks up on it," and it works fine.

Now why didn't I think of that?