My laptop often runs for at least 4 hours a day, sometimes 8-12 without shutdown, and no explosions yet ;-) but I do take good care not to block the ventilation ports and such. The only bad thing, is the 'palm prints' on the thing from my hands... Whether from heat + pressure or just extreme use, but it's a purely cosmetic issue (cheap plastic external casing).
Personally if the laptop is capable of proper cooling, and placed in the appropriate environment, I don't see any reason why a laptop can't handle a long uptime. As long as it's properly made and can offer a decent
MTBF rate for her parts.
You also might want to check out these threads here:
__________________
My
Journal
Thou shalt check the array bounds of all strings (indeed, all arrays), for surely where thou typest ``foo'' someone someday shall type ``supercalifragilisticexpialidocious''.