Our "lemon clause" is 3 major failures within 6 months. If they're spaced out more than that, or determined to be accidental damage, they don't count.
As an aside, this is why we spec 4 year warranties and accidental damage coverage nowadays. A 3 year old laptop, no matter how good, can start to show its age, especially if it's heavily used. I own an R40 that had to get its lid latches replaced, and a new mainboard because the power pin and Ethernet jack weren't holding cables anymore. Doesn't mean it's unreliable.