This article was previously published under Q311720
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The Dasetup.exe program, when used with the /u switch, may not correctly roll back Microsoft Data Access Components (MDAC) to the previous version. You can verify this by using the Component Checker utility which is available at the following Microsoft Web site:
When the MDAC setup encounters errors during the installation process, the expected behavior is to roll back any files and settings changed during installation to their original configuration. However, a known issue with Windows 95, Windows 98, and Windows Millennium Edition (Me) systems prevents this rollback from occurring correctly.
If certain errors are encountered during MDAC installation (for instance, Msxml3.dll is not registered correctly), the MDAC installation completes and reports success even though the installation was not entirely successful. Because the MDAC state on the computer is not a clean installation, subsequent MDAC rollbacks may fail.
On Windows 95 and Windows 98, you can use Component Checker to reconfigure the MDAC components on a computer as an alternative to the Dasetup.exe rollback method.
There is no workaround on Windows Millennium Edition (Me) if Dasetup.exe rollback fails. In this case, contact Microsoft Product Support Services.
For additional information on how to reconfigure MDAC components, click the article number below to view the article in the Microsoft Knowledge Base: