Not all rows importing on demo site

using drupal 6 & civicrm2.2.2

Problem importing contacts via csv file (only a portion will import)

If my csv file has 150 contacts only 63 rows will import.

I reduced csv file to 40 contacts, removed any empty columns-
only first 15 rows will import. In case one row was causing a problem I deleted rows 13 to 18
and still only first 15 rows imported.
when I check the csv created in sites\default\files\civicrm\upload (exportfilename21_730816116f5427cd5ac5b1377bd88cc7.csv) it has all 40 rows
when I check the database table (civicrm_import_job_9bf4edfcd940669ce9dde3eca0e6e2dd) it has only 15 rows.

there are no individual contacts in the database (only orgs) and I am doing no duplicate checking.

I tried the 40 record csv in the demo site and only the first 15 rows imported - which I guess suggests some problem with particular rows in my csv file
BUT I can pretty much grab any rows to make a file of 40 and only the first 15 will import.
A file of 18 rows will import OK suggesting timeout issue? but the why would 63 out of 150 work OK?

I attach 40 record file that I tried on demo site