SQL Server Setup Log
This log shows which SQL server components were detected, the operating system environment, the command-line parameters that were specified, the values that were specified, and the overall status of each MSI and MSP file that was executed.
Filename: Summary.txt
Location: %ProgramFiles%\Microsoft SQL Server\90\Setup Bootstrap\LOG
SQL Server Error Log
This is one of the most useful logs. SQL Server retains 6 previous logs. A new error log is created each time an instance of SQL Server is started
File name: ERRORLOG
SQL 2005 Location: %Program-Files%\Microsoft SQL Server\MSSQL.1\MSSQL\LOG
SQL 2008 Location: %Program-Files%\Microsoft SQL Server\MSSQL10.x\MSSQL\LOG
To Open: Start > Run > SSMS > Expand Databases > Management
Windows Event Log
The Event Viewer is an important resource for resolving SQL Server errors. There are 3 helpful logs.
Application Log: Logs SQL Server and SQL Server Agent events
Security Log: Records authentication information
System Log: Logs startup and shutdown info.
To Open: Control Panel > Administrative Tools > Event Viewer