Deleting temporary files on your computer will recover some hard drive space and in some cases, get rid of application errors.

Most people are familiar with temporary Internet files.  You can easily delete these files using the "Internet Options" utility. 
Launch "Internet Options" by clicking on the "Internet Options" option on the "Tools" menu within Internet Explorer.  Go to the "General" tab and click on the "Delete Files" button.  Enable the "Delete all offline content" check box when prompted and then
click "OK".  Depending on how heavy of an Internet user you are,
it may take anywhere from a couple of seconds to a couple of minutes for this process to complete.

To remove these files, you should first close all open programs.  Then you open "Windows Explorer" or "My Computer", browse to the folder(s) that stores these temporary files and delete the entire contents of the folder including any subfolders contained within the folder.  Don't perform this procedure unless you are very comfortable using the "Windows Explorer" or "My Computer" utilities.

The first folder to empty is the "Temp" folder off of the main Windows folder.  This folder exists in all versions of Windows from Windows 95 on up.  The main Windows folder may very depending upon your operating system.  Typically the temp folder will be C:\windows\temp\ (This is the path usually used by Windows 95/98/ME and Windows XP) or C:\winnt\temp\ (this is usually the path used by Windows NT 4.0 and Windows 2000).  However, it can vary depending upon the name of the folder in which Windows was installed.  I've seen Windows 98 computers that have been upgraded to Windows 2000 Pro that still use the C:\windows\temp\ path instead of the C:\winnt\temp\ path.  Windows can sometimes be on other drives besides C: as well so you may have a path like D:\windows\temp\ instead.

If you have Windows 2000, Windows XP, or Windows Server 2003 for your operating system, there is also a secondary temp folder that can be emptied as well.  It's below the main profile path for your user account.  For example, if you login to your computer as "Bill", this path will usually be C:\documents and settings\bill\local settings\temp\.    However this path can vary depending on your user name and the drive on which Windows is installed.  Sometimes this path can be slightly different in an office environment where the computer is a member of the domain.  For example, if you login to your computer as "Bill" and the computer is a member of the "ACME" domain, the path may be either C:\documents and settings\bill\local settings\temp\ or C:\documents and settings\bill.ACME\local settings\temp\. 

If you have Windows 2000 or Windows XP and aren't sure where your profile folder is, open a command prompt:
          Start -> Run -> Cmd
At the command prompt, type the following key sequence:
          SET<ENTER>
where <ENTER> means to hit the Enter key.  Also, it doesn't matter what folder you are currently in when you execute the "SET" command.  The SET command will display a list of environmental variables.  Look for the variable called "USERPROFILE" because this will display your profile path.  When you are done, close the command prompt window.

Sometimes when you are deleting the contents of a Temp folder, you will get a message stating that a particular file can't be deleted because it's currently in use.  This is fairly common and is nothing serious.  This usually means that there's a program that running in the background that's holding a temporary file open.  You can leave the file or files that are in use alone and delete all of the remaining files in the folder.