RichardKing

Stop VSS when defragmenting NTFS volume was unchecked. I checked it and reran Defraggler. I have regained the lost 50GB. Thank you for your assistance.

By the way, I have run Windows Chkdsk on a restart and it did not report any disk errors or bad sectors. I have not downloaded and large files recently or installed / updated any software.

Normally when I run Degraggler (V2.18.945) I gain some free space on my 1TB hard drive (C:) Yesterday I lost approx. 50GB of free space. I am running WIndows 7 Pro, 64Bit

Thanks Bluefoot, your solution fixed the problem. It is a pity the good techie folks at Piriform could not have figured it out.

Thanks for reply AP, yes the "Run as Administrator" is unchecked

I have tried V322 with the "Skip User Account Control Warning" both selected and unselected. It makes no difference, the bug I originally described still exists. After many years being a very satisified user of this software, it appears I will have to look for an alternative.

The latest version, V322, still has this fault. Yet again I have had to revert to V318.

I have just installed V321. The problem re Standard User Accouts still exists. When I run CCleaner in a Standard User Account it prompts for an administrator's password and cleans the administrator's files, not the current user's. I have again reverted to V318. When is this bug due to be rectified?

My issue is not concerned with the 32bit / 64bit debate. The problem is witht he latest versiobs V319 and V320. When I run either of these in a Standard User account, the UAC forces me to enter an Administrator password and then cleans the data for that Administrator account rather than that for the Standard Account. That is why I have reverted to V318, which when run in a Standard Account does not issue the UAC prompt and cleans the data for the Standard Account, as expected.

The latest version of CCleaner, V320, still has this bug. I am continuing to use V318.

I have reverted to CCleaner V3.18.1707 which cleans Standard Account files witout the UAC prompt.

WIndows 7 64bit Professional CCleaner v3.19.1721 (64bit) Options / Advanced / Skip User Account Control Warning selected. When I run CCleaner in my own account, which is an Administrator Account, I still get the UAC pop-up and have to click on Yes to proceed. The program works fine after that. If I run CCleaner in a Standard Account, the UAC pop-up also prompts for my Administrator Account password and when it runs it clears the files for that account rather that the Standard Account. This also happens if I enable the built-in Administrator Account, except it clears the files for that account. If I turn User Account Control off completely via the WIndows Control Panel, CCleaner will run correctly in both Administrator and Standard Accounts, clearing the appropriate files. This problem did not exist on my previous WIndows XP Professional SP3 computer. I have read other posts in reference to UAC, but they do not help to solve this problem.