nuno rodrigues, i have the same problem of table corruption like you. the reason is due to the local network traffic. when working in network environment if the electric power stops it can produce some consequences on tables. the first solution is to use inverter (onduleur in french).
but the best solution is to buy the utility CMREPAIR.EXE. this is a wonderfull utility to repair tables. see
www.cmstory.com.