Okay, I'm digging up old topics...
I'm having the same problem, and I tried to add the line of code as advised above, but now I get a different error:
Warning: str_repeat(): Second argument has to be greater than or equal to 0. in /mnt/w0608/d13/s08/b022a490/www/buyit/catalog/includes/modules/payment/authorizenet.php on line 205
Any ideas?
I can post the code in authroizenet.php if needed.
Thanks in advince!!
Noah G.