Error When Opening Pdf Invoice


I have a quick question. Our ordering processing system is working perfectly until today when I received an order that had unusually many product items.

The payment and the order itself was processed correctly, but when I want to open/print the invoice I get the following error.

[color=#000000][font=Times][size=1]Warning: DOMDocument::loadXML() [[/size][/font][/color]domdocument.loadxml[color=#000000][font=Times][size=1]]: Empty string supplied as input in /home/stores/ on line [/size][/font][/color]22


[color=#FCE94F][font=Times][size=1] ! )[/size][/font][/color][color=#000000][font=Times][size=1] Fatal error: Call to a member function node_type() on a non-object in /home/stores/ on line [/size][/font][/color]91

Can you help, what could be causing this, kindly let me know if you need more information.