I have had the same problems with this mod since I upgraded to 1.5.0. I created the google_merchant_center_feeder.txt and now my error log shows this:

[26-Oct-2012 10:51:35] PHP Warning: fread() [<a href='function.fread'>function.fread</a>]: Length parameter must be greater than 0 in /home/danielos/public_html/includes/classes/google_base.php on line 82