WindirStat was showing as "unknown" and classifying it as a .cab
BUT I just there now I decided to Disable my Shadow Copy on that drive and that was it.
It's gone. The strange thing is that I had 25 GB allocated for Shadow Copies but this was well exceeded in that file, over double the size. (I had the Shadow disabled on the C Drive only active on the D Drive)
Any way I'm happy - I have recovered 55gb space for now!!
Edited by Nigel Cardwell, 16 June 2011 - 11:47 PM.