I believe that owning a cat CAN make you mentally ill. LOL. Just ask my cat!
Cats can cause computers to do down. This is photographic evidence of a cat causing a computer malfunction.
My cats drive me crazy! They expect me to open doors for them hundreds of times a day, in and out like children. They expect me to wait on them hand and foot in every way of course. They also constantly remind me that I am not taking care of them up to their standard and am much to slow in responding to their needs. I love my kitties though and I guess when they get me properly trained it will get better.