School computers are rarely ever properly taken care of due to under paid lazy IT people. I would know, I ****ed with the IT team at my high school bad. It took them 2 weeks to fix a (oddly enough) Lenovo computer. All I did was crack the admin password for the whole school to gain full access to the computer, take off their monitoring software, remove Cleanslate, install SP2 and updates, install new drivers, install cracked updated copies of the software they had, install a WoW private server, run F@H, then customize the whole XP theme.
If they are i7s like you say, then odds have it they aren't overheating. The software being run in them is causing lock ups for whatever reason. The only way for an untouched OEM machine to overheat is:
Completely clogged of dust
CPU fan failure (unlikely) or
TIM dried up.
Since the age, it is highly unlikely of the last 2.
Schools install a ton of software to keep kids from getting into bad places like browsing 4chan or downloading an ass load of CP. Back in 2005 my school for its age and how poor it was took a great deal of care to keep kids from doing naughty things on the PC.
Besides all that, their name is still well known in the working industry where it counts. They don't make particularly bad or faulty products aimed at the usual consumer.