You can use add/remove to repair explorer but you may want to run scandisk
first.
You can repair the installation however.
Try here:
http://support.microsoft.com/default.aspx?scid=kb;en-us;318378
To download Internet Explorer 5, 5.5, or 6 for a different operating system
by using a Windows 95, Windows 98, Windows Me, or Windows NT 4.0-based
computer, follow these steps:
If you have not already done so, download the Internet Explorer Setup file
(Ie5setup.exe or Ie6setup.exe) from the following Microsoft Web site:
http://www.microsoft.com/windows/ie/download/default.htm
Follow the instructions on your screen until you receive a prompt for the
installation type.
Click Customize Your Installation, and then click Next.
Click Advanced, click Download Only, and then click Next.
Click the appropriate operating system check boxes to select them, click
Next, and then follow the instructions on your screen to download Internet
Explorer 5 Setup files for the selected operating systems.
Additional Information
Correct. A version of IE6 is implicit in XP.
And a version of IE6sp1 is implicit in XPsp1.
You can if you want uninstall XPsp1 and then install
IE6sp1 separately. Then you would see IE6sp1 listed
in Add/Remove Programs.
If you need more help with your versions open an IE window
and capture the output from these two commands:
javascript:navigator.appVersion
javascript:navigator.appMinorVersion
Note: both property names are case sensitive