Resolved Windows folder is 10X larger than the sum of its contents

I am working on an XP SP2 computer and noticed that the C:\Windows folder is shown as having 76 GB in it yet the contents of that folder (with hidden files showing) is less than 7 GB. The computer has a 120 GB HD and the total usage is ~95 GB. Diskeeper shows the drive as being continuously defragged and it does appear that approximately 80% of the HD space is being used. What could account for the huge disparity between the actual amount of data in the C:\Windows folder and what is displayed by Windows Explorer\Properties?

 

I would first run a chkdsk /f on the drive before doing anything further. That may fix it.

 

After running CHDSK/F several times the C:\Windows folder dropped in size from 75 to 72.3 GB; a relatively insignificant change. Lacking any other suggestions I will revert to a previously cloned Hard Drive and copy the data on the current Hard Drive to the clone.

 

Malware perhaps ?

Please head over to Malware and Antivirus Removal for an expert opinion.

 

I recently solved my issue regarding the size of the Windows folder.

I used xxclone.exe to show me the space allocations for all files and folders on the computer. At that point I realized I was not previously seeing the Windows\Installer folder. It turns out that the size of that folder was the missing link to the discrepancy in my calculation of the Hard Drive space utilization.

I subsequently found that many other Windows users had already discovered that their Windows\Installer folder was excessively large. The recommended solution that follows was found at http://falcon1986.wordpress.com/2010/06/26/how-to-free-disk-space-windows-installer-data-files/

1. Download the Windows Installer Cleanup Utility (msicuu2.exe) and run the installer. The corresponding entry is placed on your Programs menu, but we won’t be accessing it via this route.
2. Launch a command prompt by going to Start > Run > cmd and press ENTER.
3. You need to enter ‘C:/Program Files/Windows Installer Cleanup’ via the command prompt and then press ENTER
cd C:\Program Files\Windows Installer Clean Up
4. Enter the following command and press ENTER.
msizap !G
5. Exit the command prompt and re-check the size of C:/WINDOWS/Installer/.
The G parameter instructs msizap.exe to clean up orphaned files, which happened to be the cause of the heavy disk space usage. The exclamation mark suppresses confirmation prompts.

I ran this on my own computer and it downsized the \Windows\Installer folder from 25GB to 1.7GB.