There could be a number of reasons why your computer is slow, as already mentioned - viruses, need to download a cleaner, your server or your computer memory might be getting full. I can relate to how frustrating computer problems are. When mine is finally done for good, I'll take great satisfaction tossing it out the upstairs window.

My navigation system in my car frustrates me to no end and when its no longer fixable, I'd like to bash it with a hammer lol. You have to press okay to get the system going and its moody - can't simply press okay...I have to touch the right bottom corner just right or nothing. It also can't be trusted to get me where I want to go - what good is a navigation system, if it makes me lost.