Apologies for the repeated post, but I thought this would be worthy of it's own post in case people aren't following older threads.
This should (hopefully) now be fixed. I've tested it ok in Safari, Firefox and IE ok.
It required some brute force header generation repair -- for the techies in the crowd they were doing some pretty bizarre things with the attachment headers like having newlines in them (??) and trying to force as inline downloads (??). I set it to use something a little more sane and it seems to be happier now.
If it adversely affects any other functionality or anyone has problems with viewing attachments please drop me a PM.
Mark