Mac logging off?

[Daniel97]

Everytime I leave my mini unattended downloading files it logs me off.

I am the only user on the mac. I have caffeine running and the tick box unchecked in security settings that says log me off ..

Really I am stumped! Any ideas?

 

[stridemat]

What Energy Saving settings do you have selected?

 

[Daniel97]

Computer to sleep at 15 mins but caffeine is on