Unregister and re-register the SQLDMO.dll file located in C:\Program Files\Microsoft SQL Server\80\Tools\Binn\ (32-bit operating systems) or C:\Program Files (x86)\Microsoft SQL Server\80\Tools\Binn\ (64-bit operating systems).   If the SQLDMO.dll file is not present in either of these locations, then install the SQL Server 2005 Backwards Compatibility components.

If the issue persists, then complete the following steps:
  1. Manually detach any databases from RE_EXPRESS.
  2. Uninstall RE_EXPRESS (SQL 2005) via Add/Remove Programs.
  3. Install RE_EXPRESS manually.
  4. Ensure that the TCP/IP and Named Pipes protocols are enabled.
  5. Re-attach the databases to RE_EXPRESS.