Taxonomy_XML CSV import : Failed to Load Vocabulary

Hi,

We are devloping a multi user content management system and we have to import a few large taxonomies.

I have tried the three ways to import them. With XML and CSV with the Taxonomy_XML module and the Taxonomy_CSV modules.
With XML it will import the terms but not build a hierachy. With Taxonomy_XML CSV I have had it work well with a tiny sample, but I tried to load a 5+ mg file and I just get the error, 'failed to import vocabulary'. WIth taxonomy_csv I get an access denied error which had been reported as an error in the batch code. Another problem for another time. Is there a file size limit for importing? If so what are the right size chunks? I feel if they get too small, the chunks chunks that is, then it makes importing with a module not seeminly expedient.

The server has 2gb of ram and the php ini is set to 100mg files to upload. The upload time is set to 90 seconds.

Thanks