Upload & Sell: Off
Thanks for that heads up, Brian! I'm using PSE9 as well and have not yet upgraded to PSE10 because, frankly, since I got LR3 I very seldom export anything to PSE. But that's not to say that I want to be without it if LR4 doesn't work with PSE9. So I'll upgrade to LR4 first, then to PSE10 (especially if I encounter the same error you did!)
All that just to say thanks.