Only 23 MB remaining on hard-drive

I have a serious problem with my BBB: at startup it tells me that there is only 23.2 Mb free hard-drive (eMMC). It is about 3 Mb less at every boot.

That is, in two or three weeks, I have 0 Mb.
I do not save any files on the hard drive, but the system may save some LOG-files.
I use the original Angstrom and have only installed ntp.
I have a 1 GB microSD card that I can use, but BBB clearly do not count that as hard-drive.
(Although it is mounted in the file structure)

Help, … anyone??

Greetings
Poul C

PS.: As you can imagine I’m completely new to Linux

Check the log files. I got mine a week or so ago and whenever I had the usb connected
to my PC there was a constant stream of debug messages coming out from the usb
gadget driver.