from http://www.theeldergeek.com/repair_reinstall_ie_and_oe_6.htm

Repair or Reinstall Internet Explorer6 and Outlook Express 6

According to Microsoft, if you are having trouble with either Internet Explorer 6 or Outlook Express 6 because of damaged files or missing registration information (XP registration trouble, not your name and address) you will need to either reinstall or repair the affected installation. I'm going to go over two ways that Microsoft suggests for dealing with IE6 and OE6 problems. Read over the entire article before making a decision about which method to use. At the end of Method II I've mentioned what I'd consider the best solution to this problem.
Method I

One likely cause of IE6 and OE6 not functioning properly is a corrupted file. Microsoft says this is the "most" likely cause, but I think that's wishful thinking. To run a check on the files and see if one or more is corrupted use the System File Checker that is included with Windows XP.

Click [Start] [Run] and type sfc /scannow in the [Open] box.
(Note that there is a space between sfc and /scannow)

In all likelihood you will be prompted to insert the Windows XP CD ROM. If you don't have it available there is no point in continuing unless you have the files available on your hard drive and have changed the location of the XP installation files in the registry. If you do have the files copied to the hard drive, the default install location may be modified using the registry edit shown below.

[Start] [Run] [Regedit]
Registry Key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Setup
Modify/Create the Value Data Type(s) and Value Name(s) as detailed below.
Data Type: REG_SZ (String Value) // Value Name: SourcePath
Setting for Value Data: [Set using the path to the installation files, i.e. G:\WXPCCP_EN]
Exit Registry and Reboot

Running System File Checker is not a fast process. The machine I use for the majority of my everyday work is only a P-III 866 with 784MB RAM and a 20GB/5400 RPM C drive and it took between 7-8 minutes running off the hard drive. Expect much longer times if you run from the CD. Once the System File Checker has finished, reboot and test to see if the problem has been resolved. If the problem still exists you have three choices.

In-place upgrade of Windows XP

Repair Windows XP

Reinstall Windows XP

Since I'm 100% against upgrade installations of XP I won't recommend that option. A repair of Windows XP may solve the problem, but the fact the problem arose in the first place makes me suspect of the current installations overall integrity. I suggest a complete reinstall of XP after backing up all data files. However, before you select any of the above choices, look at Method II below.
Method II

The second method to try and correct the problem involves editing the registry and reinstalling Internet Explorer 6. The standard cautions apply whenever you are editing the registry. If you need help on how to backup the registry, click here.

If you are having problems only with Internet Explorer 6, proceed as follows:

[Start] [Run] [Regedit]
Registry Key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{89820200-ECBD-11cf-8B85-00AA005B4383}
Modify/Create the Value Data Type(s) and Value Name(s) as detailed below.
Data Type: DWORD // Value Name: IsInstalled
Setting for Value Data: [Change the Value from 1 to 0]
Exit Registry

If you are having problems only with Outlook Express 6, proceed as follows:

[Start] [Run] [Regedit]
Registry Key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{44BBA840-CC51-11CF-AAFA-00AA00B6015C}
Modify/Create the Value Data Type(s) and Value Name(s) as detailed below.
Data Type: DWORD // Value Name: IsInstalled
Setting for Value Data: [Change the Value from 1 to 0]
Exit Registry

If you are having problems with both Internet Explorer 6 and Outlook Express 6, proceed as follows:

Change the values in both of the registry keys as outlined above.
Exit Registry

Once you have made the appropriate registry changes use the link below to download and install Internet Explorer 6. The Internet Explorer 6 download includes Outlook Express 6. Reboot and test for proper operation.

Download Internet Explorer 6

It's my site so now I get to tell you how I'd deal with this situation. Really, neither of the methods above that Microsoft recommends are bad, but my approach would be to first run the System File Checker from Method I, but stop short of doing any of the upgrade, repair, or reinstall options. If that didn't solve the problem, I'd go to Method II and reinstall IE6 and OE6. If that still didn't solve the problem I'd head back to Method I and do a complete reinstall of XP. It's still my contention that piling fixes and repairs onto a damaged operating system is just postponing the inevitable reformat.

 

I received an interesting e-mail in regard to the procedures listed on this page. I haven't actually tried the procedure as it was described by the user, but it makes sense and could easily be a very valuable piece of information to have tucked away. The e-mail is below. My thanks to Socrates for sharing this information.

Hi,

Partly thanks to your site I can send this e-mail because my Outlook Express malfunctioned. But I had to add some trick I "discovered" myself which, in my opinion, should be added to the relevant TEG-page (http://www.theeldergeek.com/repair_reinstall_ie_and_oe_6.htm). 

To be as short as possible: my OE said it missed the file MSOE.dll or something, so I went looking and found that page. I did the System File Checker (no result), and then did the OE-only registry trick. Having downloaded the IE-installer, it said it found a newer version of IE on my computer so it didn't reinstall OE (and, of course, IE neither). IE functioned properly so I didn't want to spend time on a complete IE/OE reinstall (I assume I would lose my own IE settings, so therefore I refrained from doing that). 

Trying to find some sort of /repair switch with the IE-installer (ie6setup.exe downloaded from the Microsoft website), which did not exist, I tried the /? switch in the run box which revealed a box, saying there was (amongst more) a /Q switch which disabled the installer prompt. And woohoo! without the prompt the installer seemed to skip the version check and went over to the OE reinstall, leaving IE untouched and here I am e-mailing again. (Oh, there was no reboot necessary after the reinstall, it OE worked well right away.)

So, in short: consider to add the remark that entering the IE-installer path in the Run box and adding the /Q switch will prevent the installer from checking upon the installed IE version.

Sincere greetings (because of respect for your website :)),

Socrates