you have see it both way at the same time just to be sure. If your pc slow down a lot these few days, i'm sure you will suspect an attack (external, viruses in pc) or it's probably your pc needs a doc to fix its registry (an internal problem).
There are many things that science cannot explain. But, the wise will take notice of the strange behaviour and go both way. Psychological problems are normal. So, most people will likely to dismiss the second option that he's probably possessed or attacked by the 'supernatural' (actually these things are part of nature for many thousands of years).