I forgot to mention in prior post that the line in authorizenet_aim.php where the offending line of code had to be corrected is at about line 280.
Incidentally, I only became aware of this solution because, by chance, I happened to finally speak with a tech support agent at Authorize.net who actually knew what he was talking about. Each of the agents I had spoken to earlier didn't have a clue and claimed the problem wasn't theirs. So, if you are an Authorize.net customer and have a problem getting their tech support to be helpful (always PHONE them, NEVER rely on their on-line support except on weekends), just hang up and redial 1-877-447-3938 option 1, then 4. If you're lucky, on the next call you'll get someone else to help you, hopefully someone as smart as the guy I finally got.
- Roger