Corrupted Cache - Internet Explorer

from the author of 

PurgeIE - Purge Cache, Cookies and Tracks for Internet Explorer

Windows 8 Note  -  PurgeIE, PurgeIE Pro and PurgeFox were designed to work with Microsoft's Internet Explorer. Prior to Windows 8, Internet Explorer utilized files named Index.dat for indexing the Cache, Cookies and History information.

Beginning with Windows 8, Index.dat files are not used. The indexing functions are implemented within a Microsoft database system. The programming interface routines used to access the Index.dat files now function for the database system.  The default structure for the Primary I.E. Folders below is used in Windows 8 except for not containing the Index.dat files.


There are a lot of entries in Google "Groups" (newsgroups) advising Internet Explorer users to boot to DOS and to run "DelTree.exe" to delete the various I. E. folders.  This advice has been given for a variety of problems that fall into what is generally referred to as 'Corrupted Cache'.  In many instances the givers of the advice do not account for the great number or variations in the directory structure used for the I. E. folders.  For many, the folders they are advised to delete do not exist on their system.  


Problems using DelTree

Many new computer users are not familiar with DOS and enter into a state of fear when told that they must 'boot to DOS' and enter commands.  

Theoretically, DOS does not exist on the Win-ME system or the newer Windows systems.

DOS can not access the NTFS disks that are an option when running NT-4 or Windows-2000.

Deltree.exe is not distributed with NT-4 or Windows-2000 systems.  One would need to use the 'RD' command instead.


The Primary I.E. Folders and the Index.Dat Files

Each of I.E.'s primary folders (directories) - Cache, Cookies and History make use of an indexing technique to maintain information. The index information is contained in files named Index.dat.

For Cookies and for Cache, the Index.dat files are basically pointers to real files. For History, no files are referenced (this is the collection of URL entries used for AutoComplete and for controlling the highlighting of imbedded links on the Web pages). All three contain the actual URL plus date/time stamps and reference counts.

Data errors can occur within the Index.dat files and they can get out of sync with the files they reference. Power failures, System failures and improper shutdown procedures can cause the data errors. Data errors can also occur within the actual data files. Any of these are considered to be corrupted cache.


The Default Structure of the Primary I.E. Folders

Cache Folder:

<base>\temporary internet files\content.ie5  [dir]
<base>\temporary internet files\content.ie5\
Index.dat
<base>\temporary internet files\content.ie5\..random1..  [dir]
<base>\temporary internet files\content.ie5\..random1..\..cache files..
                   - - - - - - - - - - - - - -
<base>\temporary internet files\content.ie5\..random8..  [dir]
<base>\temporary internet files\content.ie5\..random8..\..cache files..

Cookie Folder:

<base>\cookies  [dir]
<base>\cookies\
Index.dat
<base>\cookies\..cookie files..

History Folder:

<base>\history\history.ie5  [dir]
<base>\history\history.ie5\
Index.dat
<base>\history\history.ie5\mshist01..  [dir]
<base>\history\history.ie5\mshist01..\
Index.dat
            - - - - - - - -
<base>\history\history.ie5\mshist0n..  [dir]
<base>\history\history.ie5\mshist0n..\
Index.dat

Notes -

[dir] indicates that the line represents a folder (or directory) name.

The folder levels 'content.ie5' and 'history.ie5' were introduced with IE-5. They are not used in IE-4.

The Index.dat file within the Cache folder is used to contain URL names, date and time stamps, and pointers to the actual cache files which are spread among the four to eight cache sub-folders. These sub-folders are named with randomly-generated 8-character names.

The Index.dat  file within the Cookie folder is used to contain URL names, date and time stamps, and pointers to the actual Cookie files which are stored within this same folder.

The Index.dat  file within the uper level of the History folder is used to store 'Visited' URL names, date and time stamps. This is the data used by I.E. for its AutoComplete function and controlling the highlighting of imbedded links on the displayed Web pages.

There is one 'mshist...' file for each day of history that you have instructed I.E. to retain. The daily history is stored in the subordinate Index.dat  files.

For the above, <base> illustrates the base portion of the path to the folder. This varies widely between the various combinations of Operating Systems and I.E. versions.

For the simplest systems without user profiles, it could be:  "C:\windows"

For a Win-9x system with profiles, it could be:  "C:\WINDOWS\PROFILES\login-name"

For a Win-2000 system, it could be:  "C:\DOCUMENTS AND SETTINGS\login-name\LOCAL SETTINGS" 


Symptoms of Corrupted Cache

There may not be a comprehensive reference for the symptoms.  Some of the more common ones follow:

This list is expected to grow over time as other symptoms are identified.


"PurgeIE" to the Rescue

"PurgeIE" contains an Emergency function for deleting the I.E. folders so as to simplify handling of corrupted cache.  This was  included due to the difficulty in describing a foolproof manual process for some newcomers to the PC.

The Emergency function is accessed by pressing the "Tools" menu option and selecting "Purge I.E. Folders at next Reboot".  As indicated by its title, you will have to reboot to complete the process. You can select to purge either, or all, of the three primary I.E. folders.  Also, you have the option to only delete the Index.dat files in these folders.

If you wish to try retaining your Cookies, you could try deleting only the Index.dat file within the Cookies folder.  IE-5 and IE-6 will then build a new Cookie Index.dat file from the Cookie text files.  

NOTE - Apparently, IE-7 does not populate the new Index.dat file from the Cookie text files.


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Revised: January 19, 2013