KB Article: http://support.microsoft.com/kb/949220
You may receive an error message when you try to install Internet Explorer 8.
The following methods are only for general problems. We recommend that you try from easier methods. If you still have the problem after you use these methods, contact Microsoft Support.
Note Before you try the following methods, make sure you have meet the Prerequisites of Internet Explorer 8 installation.
Method A:Reset Windows security settings back to the defaults (Rated: Easy)
Method B:Scan your computer for malware (Rated: Easy)
Method C:Temporarily disable antispyware and antivirus software (Rated: Easy)
Method D:Start your computer in a "clean boot" state (Rated: Moderately easy)
Method E:Check for any files that cannot be backed up or updated (Rated: Moderately