Preventing the X120e from sleeping

[SailingAway]

I have an X120e running Windows 7 Professional. I'm currently using it as a temporary file server, so I would like to have it on and running all day. I've noticed that during periods of inactivity, it will either shut itself off or sleep. I went into Window's power options control panel and set all the relevant settings to have it remain on but it hasn't helped. I also went into the BIOS but didn't see any specific options regarding this matter. I don't have Thinkpad's power management utility installed, just using Window's own power options. The laptop is in a well ventilated area so it's not shutting down due to overheating.

Can anyone suggest how I can keep the laptop on all the time?