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Internet Explorer could not be installed
http://www.vistaarticles.com/articles/115/1/Internet-Explorer-could-not-be-installed
By 
Published on 11/23/2006
 
Describes an issue that may occur when the Setup program cannot modify the registry.

Internet Explorer could not be installed

Method 1
If you use any antivirus or antispyware programs, disable them before you install Internet Explorer 7. Then, re-enable them after the installation has finished. For example, to install Internet Explorer 7 on a system that has Webroot SpySweeper installed, you must first disable the IE Hijack shield. For more information about how to disable the IE Hijack shield, visit the following Web site:
http://support.webroot.com/ics/support/default.asp?deptID=776&task=knowledge&questionID=2661 (http://support.webroot.com/ics/support/default.asp?deptID=776&task=knowledge&questionID=2661)
Some antivirus and antispyware programs prevent Internet Explorer 7 from successfully installing, even when the antivirus and antispyware programs are disabled. For more information about these issues, visit the following Microsoft Web page:
http://msdn.microsoft.com/ie/releasenotes/default.aspx

Method 2
1. Determine whether there is a problem that prevents the registry from being updated:a.  Click Start, click Run, type %windir%\ie7.log, and then click OK to open the ie7.log file.

Note By default, the ie7.log file is located in the C:\Windows folder. 
b.  Press CTRL+END to move to the end of the ie7.log file.
c.  On the Edit menu, click Find.
d.  In the Find what box, type IECUSTOM: Key is still unwriteable.
e.  Under Direction, click Up, and then click Find Next.

If you find the "Key is still unwriteable" text, this indicates that there is a problem that is preventing the registry from being updated. For example, text that resembles the following in the log file indicates that there is a problem:
time_stamp: IECUSTOM: Key is still unwriteable registry_subkey
In this example, registry_subkey is the name of the registry subkey that is causing the problem. 

If you do not find the "Key is still unwriteable" text in the ie7.log file, go to step 2 for additional troubleshooting steps. 
2. Reset the registry permissions for the registry subkey that has the incorrect permissions. To update the permissions of the registry subkey, follow these steps: a.  Click Start, click Run, type regedit, and then click OK. 
b.  Locate and then right-click each registry subkey that you noted in step 1e, and then click Permissions on the Edit menu..

Note The ie7.log file contains the following abbreviations: HKCR = HKEY_CLASSES_ROOT
HKLM = HKEY_LOCAL_MACHINE
HKCU = HKEY_CURRENT_USER
 
c.  Under Group or user names, click Administrators. 
d.  Under Permissions for Administrators, make sure that the Allow check box is selected for the following entries: Full Control 
Read 
Make sure that the Deny check box is not selected for any users or groups.

For more information about how to modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:
310426 (http://support.microsoft.com/kb/310426/) How to use the Windows XP and Windows Server 2003 Registry Editor features 
e.  Click Apply, and then click OK. 
f.  On the File menu, click Exit. 
g.  Try to install Internet Explorer 7 again. You may have to repeat these steps if there are other keys that have permissions that prevent Internet Explorer 7 from installing.  

Method 3
1. Determine whether there is a problem that prevents the files from being backed up or updated. To do this, follow these steps: a.  Click Start, click Run, type %windir%\ie7.log, and then click OK to open the ie7.log file.

Note By default, the ie7.log file is located in the C:\Windows folder. 
b.  Press CTRL+END to move to the end of the ie7.log file.
c.  On the Edit menu, click Find.
d.  In the Find what box, type ArchiveFileForUninstall:ArchiveSingleFile Cancelled.
e.  Under Direction, click Up, and then click Find Next.

If you find the "ArchiveFileForUninstall:ArchiveSingleFile Cancelled" text, this indicates that there is a problem that is preventing an IE6 file from being saved for uninstall. For example, text that resembles the following in the log file indicates that there is a problem:
Time_stamp: ArchiveFileForUninstall:ArchiveSingleFile Cancelled
Time_stamp: DoInstallation:UpdSpCommitFileQueue for AlwaysQueue Failed: 0x4c7

If you do not find the "ArchiveFileForUninstall:ArchiveSingleFile Cancelled" text in the ie7.log file, use Method 4 for additional troubleshooting steps. 
 
2. Reset the permissions for the Vgx.dll file. To set the permissions of the file to the default, follow these steps: a.  Click Start, click Run, type one of the following commands, and then click OK: If you are running Microsoft Windows XP, type the following command:
echo y| cacls "%CommonProgramFiles%\Microsoft Shared\VGX\vgx.dll" /P BUILTIN\Users:R "BUILTIN\Power Users:C" BUILTIN\Administrators:F "NT AUTHORITY\SYSTEM:F"
If you are running Microsoft Windows Server 2003, type the following command:
echo y| cacls "%CommonProgramFiles%\Microsoft Shared\VGX\vgx.dll" /P BUILTIN\Users:R "BUILTIN\Power Users:C" BUILTIN\Administrators:F "NT AUTHORITY\SYSTEM:F" "NT AUTHORITY\TERMINAL SERVER USER:C"
 
b.  Try to install Internet Explorer 7 again. If the problem is not resolved, go to the next workaround method.  

Method 4
Use this method if you receive an error message about the Cryptographic Services that resembles the following error message:
Setup could not verify the integrity of the file Update.inf. Make sure the Cryptographic service is running on this computer
For more information about what to do if you receive this error message, click the following article number to view the article in the Microsoft Knowledge Base:
822798 (http://support.microsoft.com/kb/822798/) You cannot install some updates or programs
If the problem still occurs after you follow the steps in Microsoft Knowledge Base article 822798, your installation package may be corrupted. To correct this problem, download Internet Explorer 7 again from the following Microsoft Web site:
http://go.microsoft.com/fwlink/?LinkID=72018