Upload module breaks submit functionality on certain modules

Latest Drupal CVS as of today and upload module 1.79. Using simplenews (1.40) as example. Trying to submit a newsletter produces the following error:

Warning: Invalid argument supplied for foreach() in /var/www/modules/upload.module on line 432
Warning: Cannot modify header information - headers already sent by (output started at /var/www/modules/upload.module:432) in /var/www/includes/common.inc on line 233

Switching off the upload module removes the error and the node can be successfully submitted.

Regards

Patrick