When you start the CMS serer you may get this error.( Check in the event log)
Unexpected value for parameter DatabaseConnectString
The root server reported an error Initialization Failure.
The CMS database is not configured correctly. Configure the CMS database using the Central Configuration Manager.
Failed to write the database connection string to registry
CMS uses the libeay.dll to run. This dll is available in the Windows/System32 folder. If this dll is not available or any other new application overwrites the existing one, this error will occur.
Check this dll. I also come across this error. I have the backup of this dll. After I put the dll in the system32 folder, CMS started successfully.