Same error expericenced
Yes, I do experience the same problem. Mine is caused by the 'ç' character. The error happens on line 483 of WA_eCart_Definition_PHP.php:
$theItemArray = explode("§",$theCartString);
$theCartString is not "exploded" correctly and messes up the rest of execution.
I am going to try to solve the problem by converting special characters to HTML entities before feeding it to the database, but there is definitely a bug to solve in this portion of code with languages that use special entities.