I have noticed an annoying issue in the last few months, possibly the last six (so it could have been introduced with the Windows 10 v1803 update), and that is my hard drive space on my C drive, which is a 1 TB Samsung 850 EVO SSD used to booth Windows, drops down from 85-90 GB to 25-30 GB. It is currently showing 25 GB free! I have no idea what is using this space but it does eventually return after a few days. I do have games installed on this drive and a couple of them are updated but these are definitely not the reason for the loss of hard drive space (otherwise I would not get the space back). I've checked Steam and there is nothing in its Downloading folder. I've also ran the usual array of Disk Clean-up, CCleaner and Windows' own Storage cleaner and there is nothing more than a few hundred MBs being used by various programs, certainly nothing to account for the missing 60 GB. I've checked with WinDirStat and I cannot see anything obvious that is using this 60 GB of space, other the games that were previously installed. Has anyone else seen or noticed this behaviour?