Table corruption in MySQL can often wreak havoc on the auto_increment fields. I'm still unsure why it happens, but if you find a table tries to count from 0 after a table corruption, just find the highest key in the column and add 1 to it (in this example, I'll say the highest key is 9500).
Just run this one SQL statement on the table:
ALTER TABLE brokentablename AUTO_INCREMENT=9501;
If you run a quick insert and then run SELECT last_insert_id(), the correct key number should be returned (9501 in this case).
