ORA-01631, and table is not full, is this an index problem?

I've got a newly installde data collection instnace (7.3.4.5) that's usdenly returning ORA-01631 when data is atempted to be loged into some tables.

But, the following query, which I picked up from the O'riley "Oracle Preformance Tuning":

SELECT BLOCKS
    ALLOCATED_BLKS,

		COUNT(DISTINCT SUBSTR(T.ROWID,1,8) ||
		SUBSTR(T.ROWID,15,4)) USED, (COUNT(DISTINCT
		SUBSTR(T.ROWID,1,8) || SUBSTR(T.ROWID,15,4)) /
		BLOCKS) * 100 PCT_USED
        FROM
		SYS.DBA_SEGMENTS E,
		&&USER .&&TAB_NAME T
		WHERE
        E.SEGMENT_NAME = UPPER ('&&TAB_NAME')
		AND E.SEGMENT_TYPE = 'TABLE' GROUP BY
		E.BLOCKS ;

Says:

Enter value for user: flink
Enter value for tab_name: B410

ALLOCATED_BLKS USED PCT_USED
-------------- ---------- ----------

         17410 17219 98.9029294

And since the data being inserted is tiny, relative to the allocated table (many of them hav 1 million + rows), I'm certain that the table really does have space for the row.

I'm not quite so certain of space in the indexs, though. However I would have expected a more specific error message if it were index size related.

Anyone have words of wisdom on this?

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