Mod Edit: Split from http://www.bleepingcomputer.com/forums/t/623487/esp-1-low-disk-space-message - Hamluis.
I just started having the same issue. In my case, it is called ESP (G:) and it is 90% fragmented. However, it will not allow me to defrag. I know next to nothing about the behind the scene workings of my computer, but I just started getting the "almost out of space" message today.
Edited by hamluis, 18 August 2016 - 09:49 AM.
Split - Hamluis.