I'm running Puppy 4.2.1 on an old Acer Travelmate 525TX laptop. The intention is to use the computer as a torrent downloader using Transmission as the client; I set it up to download something, forget it exists and it sits there and does its job.
Its old hard drive is busted, so I removed it and connected an external 30GB surplus 3.5" drive through a PCMCIA USB2.0 card and I'm running Puppy from the CD (the laptop is too old to support USB booting).
Everything works as intended... for a while. But every single time I've set up a Transmission download, I come back later and find the computer off. It seems to hard-shutdown, since the NTFS filesystem of the external drive is dirty after this happens, so it doesn't get properly unmounted.

If booted up and left there idling, connected to the internet (through the built-in ethernet port) and to the external drive (through PCMCIA) but not doing anything, it stays on indefinitely. However, if I actually give Transmission something to do, it dies.

Any idea what the heck is causing this, and how to stop it?

Thanks.

Try other torrent clients. If they work, there is a high probability Transmission is broken. Otherwise, it's probably the networking system of your OS, or the hardware.