Empty Recycle Bin - If you select this check box, CCleaner will empty your Recycle Bin.
Temporary Files - CCleaner will delete the Windows temporary files which are not in use. By default it only removes files that have not been accessed in 48 hours. This can be changed to clean all temp files in the Advanced Settings.
Clipboard - CCleaner will clear the contents of the Windows Clipboard.
Memory Dumps - When Windows crashes, it stores small memory dumps so that technical users can debug their systems. CCleaner will delete these files.
Chkdsk File Fragments - These are clusters and chains that are left over after you run CHKDSK. CCleaner will delete them.
Windows Log Files - Windows logs many events and activities, such as access, policy changes, Internet use, tasks, and so on. As a result, the dozens of logs it creates are scattered across the system. They will all be deleted by CCleaner.
Windows Error Reporting - (Vista only) Whenever a program crashes, Windows saves details of the crash to report back to Microsoft. This option will clean all the error reports from your system.
DNS Cache - When you visit a Web site, Windows attempts to speed up future visits to that site by writing its DNS information to the DNS cache. This option will clear out the cache so that Windows can start storing DNS information from scratch.
Font Cache - Windows caches commonly-used fonts to optimize performance. This option will clear the cache so that Windows will rebuild it.
Start Menu Shortcuts - This option will delete Start Menu shortcuts that are invalid (they point to files that no longer exist).
Desktop Shortcuts - This option will delete desktop shortcuts that are invalid (they point to files that no longer exist).