insert & concurrent read no longer work with 5.0.27 myisam

[matt_lists]

We have been using older versions of mysql without any problem (5.0.19)

I updated our test server to 5.0.27

senario is.. temp table performs data conversion, master table is never 
deleted/updated, only new records insert, insert takes 30-40 minutes for 
bulk loads

under old mysql versions we had no table locking

under 5.0.27 the select locks, and after a few minutes I get this error

select * from table limit 1;
ERROR 5 (HY000): Out of memory (Needed 1371552 bytes)

Job running that causes the lock is, load data concurrent infile 'file' 
ignore into table

did something change?  Do we need to switch to innodb (WAY slow in test) 
to do concurrent inserts & reads?  I never delete from the tables, and 
concurrent was supposed to allow insert/read at the same time as long as 
there's no data holes, and there are none in my case, a delete statement 
has never been ran on this table, never will it's all historical data.

from the documentation..

For a |MyISAM| table, you can use concurrent inserts to add rows at the 
same time that |SELECT| statements are running if there are no deleted 
rows in middle of the table.

is this no longer the case?

I tried making it do inserts in batch form, ie 250 records at a time, 
but a 30 min load turned into a 3 hour load using that method, and it 
locks tables longer than I like.