It’s unlikely your laptop will catch fire, as a Dell notebook did in Japan earlier this summer. But nearly one-fifth of all notebook PCs will break down during their lifetime, needing a new hardware component to fix the failure, according to a Gartner study. Motherboards and hard drives fail most frequently.

Desktops suffer from the same weaknesses, but they break less often. Five percent of new desktops will break within 12 months, and 12 percent will break within four years, Gartner estimates. In comparison, 15 percent of laptops will break within a year, and 22 percent within four years.

Broken screens used to be the most common laptop failure, says Leslie Fiering, research vice president at Gartner. But manufacturers have reduced screen breakage by making the notebook casing and screen bezel more rigid, and by providing more clearance between the screen and keyboard when the lid is closed.

Now motherboards are more complex. Technicians used to be able to replace parts like a network interface card, but today such parts are integrated into the motherboard. The entire motherboard must be replaced to fix one component.

Such repairs average five days, depending on how busy technicians are, at a cost of at least $250 in lost productivity and administrative expenses.

After motherboards and hard drives, the next most common notebook hardware failures are latches and hinges on the chassis, lost key caps and the aftermath of drinks spilled on the keyboard.