The website I have just made live on Magento has crashed after one day of activity.

I have checked the error log and it begins with the following ...
a:5:{i:0;s:144:"SQLSTATE[HY000]: General error: 126 Incorrect key file for table '/tmp/#sql_dda_0.MYI'; try to repair it, query was: DESCRIBE `log_visitor_info`";i:1;s:3547:"#0

Does anyone know what this means, or can assist me in fixing this issue please?
Thanks