Q:   I have a 160GB Western Digital Hard Drive partitioned into a 40GB Operating System partition and the other 120GB for my files. However, when I run Disk Cleanup utility from within Vista Ultimate, it shows multiple 131GB options for me to clean up. After I clicked OK to cleanup the selected entries, it erased everything on the 40GB partition. I then had to reinstall Windows Vista, but the problem seems to be recurring.

(Information in this blog post applies to Windows Vista systems only)

A:   Having received three more such questions in my mail, I decided to work on this issue. Here is the screenshot of what Disk Cleanup displayed:

Fig 1: Disk Cleanup showing the list of files to delete. According to Disk Cleanup, the Windows Error Reporting files constituted to 196GB, which certainly is impossible!

I asked for the registry export of this key from one of my client’s PC:

(The above registry location contains the list of Disk Cleanup handlers and their registration information.)

Once I got the registry export, I compared it with my system and noted that a really important value named Folder was missing in each of the following subkeys under the VolumeCaches branch:

CRUCIAL NOTE

I came across this paragraph from the MSDN documentation:

Description for the Folder registry value:

A specific folder or folders to search for items matching entries in the FileList value. You can specify wildcards using the ? or * characters. If the value is of type REG_SZ, multiple folder names are separated using the | character, without spaces on either side of it. If a CSIDL value is present, only one folder can be specified in this value. The location indicated by the CSIDL value is prepended to that folder path to compose a search path. For an example, see the CSIDL value description. If this value is absent, the root folder of the current volume is used. The DDEVCF_DOSUBDIRS flag is needed in that case to search the entire drive.

Note the last line which states that the Disk Cleanup will recursively search the entire volume for the list of files mentioned in the FileList registry value (*.* wildcard used in this case) and include everything on the volume for deletion, if the DDEVCF_DOSUBDIRS flags is enabled (which is enabled by default).

FIXING THE REGISTRY SETTINGS

I created the REG file cleanmgrfix.reg to fix the Folder registry values in each of the above registry keys, and the issue was resolved after applying the fix. This is what Disk Cleanup showed:

Fig 2: Disk Cleanup screenshot, after fixing the registry values.

Editor’s Note: Although I could identity where the problem was, I had no clue on how the Folders registry value vanished in the above registry keys. My best guess is that a registry cleaner that you used may have wiped out the value somehow. At any case, have an eye on the disk space showed in Total amount of the disk space you gain: section of the Disk Cleanup window every time when you do the cleanup work.

I hope this blog post helped you avert a major problem in your system. Readers who’re using registry cleaners and experiencing this issue, please do comment on this article or send me a feedback. This would help me determine the root cause of the problem and help as many users as I can.