Sometimes when I submit a request, I get an error like this from Authorize.net:
"Authorize.net payment error for transaction 72 for user 10. Response code: 3. Response subcode: 1. Response reason code: 270. Response reason text: Line item 1 is invalid.."

I also get this error:
preg_match() expects parameter 2 to be string, array given in /home/content/t/h/e/thevicosmetics/html/includes/bootstrap.inc on line 670.

Authorize.net says that error means: (http://www.authorize.net/support/AIM_guide_SCC.pdf)
A value submitted in x_line_item for the item invalid. referenced is invalid.

And the definition for x_line_item:
It's an optional value. It can by any string. Line item values must be delimited by <|>. There's no max length.
The description is:
Itemized order information.

Any idea what can be wrong? I'm most worried about the preg_match() error.