There are many tools to delete the unknown file from your computer. Unknown file is the file that appear without your aware. One of the tool or software that can be used to delete those files is Ccleaner (2,851 kb). This freeware can be downloaded from: http://www.ccleaner.com/download

The task that can be done by this software such as clean:

Internet Explorer
Temporary Internet Files, Cookies, History, Recently Typed URLs, Delete Index.dat files, Last Download Location and Autocomplete Form History.

Windows Explorer
Recent Documents, Run (in Start Menu), Search Autocomplete, Other Explorer MRUs and Thumbnail Cache.

System
Empty Recycle Bin, Temporary Files, Clipboard, Memory Dumps, Chkdsk File Fragments, Windows Log Files, Start Menu Shortcuts and Desktop Shortcuts.

Advanced
Old Prefetch data, Menu Order Cache, Tray Notifications Cache, Window Size/Location Cache, User Assist History, IIS Log Files, Hotfix Uninstallers and Custom Files and Folders.

Firefox/Mozilla
Cookies, Download History, Internet Cache, Internet History and Saved Form Information.

Applications
Adobe Photoshop CS, Adobe Reader 8.0, MS Office Picture Manager, Office 2007 and Office 97.

Internet
Sun Java and Yahoo Toolbar.

Multimedia
Adobe Flash Player, Real Player and Windows Media Player.

Utilities
IZArc, WinRAR, WinZip and Windows Defender.

Windows
MS Paint, MS Wordpad and RegEdit.

Beside to clear the task that has specified above, Ccleaner also has the other function such as Registry Checker, uninstall software from your computer and manage your computer startup.

Registry Integrity
Missing Shared DLLs, Unused File Extensions, ActiveX and Class Issues, Application, Fonts, Application Paths, Help Files, Installer, Obsolete Software, Run At Startup, Start Menu Ordering and MUI Cache.