ERROR 3: Error writing file '/tmp/STcgTgD3' (Errcode: 28)

[JC]

I am using Mysql version: 4.0.18-max-log

and trying to populate a database from a text file using source option from
inside the mysql environment.

The population run OK but when creating the indexes i get

< ----- ERROR ------------->
Query OK, 1 row affected (0.00 sec)

Database changed
Query OK, 0 rows affected (0.04 sec)

Query OK, 5659258 rows affected (1 min 48.83 sec)
Records: 5659258 Deleted: 0 Skipped: 0 Warnings: 0

Query OK, 5659258 rows affected (2 min 29.38 sec)
Records: 5659258 Duplicates: 0 Warnings: 0

ERROR 3: Error writing file '/tmp/STcgTgD3' (Errcode: 28)
Query OK, 5659258 rows affected (3 min 52.53 sec)
Records: 5659258 Duplicates: 0 Warnings: 0

ERROR 3: Error writing file '/tmp/STMHUInL' (Errcode: 28)
Query OK, 5659258 rows affected (5 min 2.80 sec)
Records: 5659258 Duplicates: 0 Warnings: 0
< ----- END ERROR ------------->
however the script finish successfully

and "show index from tablename " command all indexes

Please help as it is driving me mad.

--
JC