I'm suddenly having a similar problem on two of my sites (both at the same host). I'm getting order payments, but no order confirmations. When I look at the site(s) there is no order in the admin.
I haven't made any changes to either site in some time. Both are 1.3.7 and the payments are going through both PayPal and Authorize.net.
Problem started a few days ago as a one-of and then today it was a regular occurrence. Also, as a late breaking developement, one of the download links got "lost" on an order that did process. Not sure if this is directly related, but it's the first time it's happened. Seems too coincidental to be happening at the same time...
I'm afraid I'm not sure where to even start looking for the problem.
TIA for any suggestions.
JodiB



