Just like with anything you'll ever purchase in your lifetime, there is a certain level of random failure with computer parts. This is a possible cause of hardware failure. Computers are very susceptible to electrical damage. With this in mind it's very important to have a good surge protector or "Uninterrupted Power Supply or UPS" (recommended). Many customers we come across could have prevented a lot of problems with a simple $40+ surge protector or UPS.
Poor computer treatment:
If you got sick, would you walk down the street screaming for help and take pills from the first person that said they would fix your sickness? Of course not! Likewise, it makes no sense to trust random internet sites that tell you to install, uninstall or alter items on your computer to fix it. Many times, customers tell us that the problem started out small but got very large after they tried a solution they found on some website. This is never a good idea, read more below...
Virus and Spyware:
Believe it or not, if you are running Windows XP with Service Pack 2 or later (most people are); then you put the virus on the computer yourself. (or someone in your home). You cannot leave the computer unattended and have a virus crawl in while you're not looking (it simply won't happen) and you cannot get any sort of virus / spyware from merely going to a website. (no matter how bad the website is). Believe it or not, at some point, someone on your computer did choose to install this virus. They may have thought they were installing an online video game, the latest audio / video plugin or it may have just been an ActiveX installation that prompted you to allow or disallow an online ActiveX install. Regardless, you or someone using your computer actively chose to install this program that ended up being a virus. This is why as a general rule of thumb, if you don't absolutely, positively need to install something, then don't.
One of the most common places virus distribute is through free online computer security and repair tools. The virus distributor knows that your computer is unprotected (why else would you be downloading free antivirus). There's no such thing as a free lunch and the few free antivirus out there that are legitimate aren't that good anyway; after all these are products that have zero funding and zero dollars to pay staff to update and improve the program, how good could they really be. The cheapest antivirus is truly the one that works well and prevents the need for computer repairs.
House Guests and Kids:
Neither are going to be very cautious with your computer. Our advice, tell the guests that you forgot your password. Kids will be reckless regardless, your best bet is a parental block that only allows them to navigate to a small list of websites.