question about create a table

[C C]

Hi,
I want to create a table using the following statement:

CREATE TABLE NonUniqRecords SELECT c.id, c.levels
FROM catalog_all c, UniqRecords u
WHERE c.id != u.id
ORDER BY c.levels DESC;

PS:Table catalog_all and UniqRecords are already in database.

However, it shows the following error message after running for 8 mins

ERROR 126 (HY000): Incorrect key file for table '#sql_d78_0.MYI'; try to repair it

Anyone can tell me why?
Thanks