I've had the same trouble you've had about a year ago. Have a look at the replies here, there are some great suggestions from people in there: CodeIgniter MSSQL connection
@StefenWiranata Sorry, just noticed part 2 of your comment - I can't remember where I'd made the change, but I can try and look tonight if you can't get it solved. I know for sure that CI was adding apostrophes around the table names somewhere in system/database/drivers/odbc/, most likely in the odbc_driver.php file.