What is my Mac Mini deleting on its own?

Hi,

Over the past 4 months I have gotten 10 or so messages saying something along the lines of "Your startup disk is almost full. Free up some space on your hard drive." I then check my finder window to see that I do have less than a GB left. However, after an hour or two, I check finder again and I suddenly have about a gig more, then the next day I have about two gigs more and then the increase stops. What is my Mac Mini deleting without my permission to free up this space?

Possibly a memory swap-file?

Yes, it's a swap-file, and more would appear when you restart.

That's not a problem. The problem is that you are ignoring a VERY SERIOUS message that is GOING to lead you to data loss if you don't take it more seriously. Too full hard drives can cause crashing, directory corruption and worse.

You need to get at least 12GB freed up, and PRONTO. Buy an external or delete a bunch of stuff or do something -- before it's too late. Sorry if I sound alarmist, but it's only because this is an alarmingly dangerous situation for your data.