Some Windows 98 and Office 2000 users report they have a very early (incompatible) version of the Windows Installer that was installed by Windows 98 or Office 2000. Check your version is 1.10 or later and upgrade, if that isn't the case, by following the directions at the /dist/httpd/binaries/win32/ downloads page.
Note: Some folks who already installed the Microsoft Installer, or are using Windows ME or 2000, report that they cannot double click the .msi file to start the installation. Sorry that your registry was somehow corrupted, but you can get around this problem by running the following command with Start -> Run...
MSIEXEC /i d:\path\to\file\apache_version.msiSubstitute the downloaded drive, path and file name. This may be a symptom that you are running an older version of the MSI installer (see above.)
Here are some links to troubleshooting pages at Microsoft, first see if any of these reports solve your problem.
To help you any further, we need to see the error log. You can make one by using the following command when attempting to install Apache:
MSIEXEC /I apache_install_package.msi /L*v YourLogFileName.txt