ok so i am about to inherit an imac g4 700mhz from a friend. the reason hes getting rid of it is that every few minutes, sometimes right after starting up, and seemingly for no reason, the screen greys and the box comes up in the middle with a picture of the power button giving me instructions on how to restart the machine in like 4 languages. what could be causing this, and is it something a hard drive wipe and clean install would help?
This is what we call a Kernel Panic, and yes a reinstall (often just an archive & install) will usually stop them from happening. They can be caused by incompatible or faulty hardware, but its usually either software or bad RAM.