'C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\SEEMSDb.mdf' because it already exists.
Something is preventing the SQL script from completing.
There are multiple solutions for this error depending on the cause listed in the installation log.
First, ensure the database user does not exist in the SQL instance.
Log into the SQL Server Management Studio
Expand the instance and go to Security
Go to Logins
If the user account you were attempting to create already exists, delete the account. (Note: This is not the 'sa' account.)
Once the account is deleted, proceed with the installation again and ensure that the password you supply the new database user is complex enough.
For the following error:
"Error executing SEEMSDb creation script: database [SEEMSDb] creation failed Cannot create file 'C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\SEEMSDb.mdf' because it already exists."
This error can occur if the SEEMSDb is not removed from SQL Server prior to uninstalling SQL Server. The mdf/ldf files will be left in the DATA directory. If you would like to proceed with a fresh installation, you will need to remove these mdf/ldf files from the DATA folder.
For all other errors, please generate a log of the installation using the following command and contact technical support.