How to Know Which Files Are Safe to Delete with Windows Vista’s Disk Cleanup

By Woody Leonhard

When your computer is running low on space, Vista’s Disk Cleanup will locate a wide variety of files that you can delete, but if you don’t know which files are safe to delete, you might delete a file that will cause you more problems than just limited space.

If you need to run Disk Cleanup, click Start→All Programs→Accessories→System Tools→Disk Cleanup.

The following table takes you through each of the file types that Disk Cleanup might find. You’ll find an explanation about what each of those file types do and a recommendation as to whether the different types of files are safe to delete.

Choosing Which Files to Clean
Type of File Contains Delete These Files?
Temporary Setup Files Vista and other Microsoft setup files. Yes
Downloaded Program Files ActiveX controls and Java applets. Typically these are small
programs downloaded from the Internet. They work with
“custom” applications: games, Web file viewers, and the
Temporary Internet Files Cached pictures and pages from Internet Explorer (not
Offline Web Pages Pages that are downloaded automatically so that you can see
them without being connected to the Internet.
Hibernation File Cleaner If you check this box, you will completely turn off the
hibernation feature in Vista.
Debug Dump Files If Dr. Watson (Microsoft’s crash reporting tool) wanted
the files, he’d have ’em by now.
Old Chkdsk Files Lost fragments of files that all the king’s horses and
all the king’s men would never be able to put back together
Previous Windows Installations System files and folders from previous versions of Windows.
Chances are good you’ll never be able to recover them
Recycle Bin A good guideline is to never delete Recycle Bin files
automatically. If you’re ready to get rid of your old files,
delete the files manually by going into the Recycle Bin.
Setup Log Files Log files generated when Vista was originally installed. Yes
System Error Memory Dump Files More Dr. Watson files that you’ll never want. Yes
System Error Minidump Files Ditto. Yes
Temporary Files Anything in a Temp folder. Yes
Temporary Windows Installation Files If the Vista installer didn’t clean up after itself,
these are still sitting on your disk.
Thumbnails The thumbnail files that sit inside every folder. Save time by
keeping them.
Files Discarded by Windows Upgrade The Vista installer puts files that it doesn’t recognize
in a specific location. Unless one of the users on your machine
lost files during the upgrade to Vista, you can delete these.
Various Windows Error Reporting Files More Dr. Watson–style files. Yes

If your Disk Cleanup list includes a box called Office Setup Files, be careful about checking the box. Some Office 2003 patches have had bugs that stumble when they find these installation files missing, which can result in a number of strange error messages. It’s best to leave these alone.