Just a comment on my own experiences - A while back it seemed to take anything up to an hour for the order to appear on my site, so don't panic too quickly.

Had the same problem this morning with one payment received but no order details, found that if you go to your Paypal account>Profile>Instant payment notifications, you can tick and resend the offending IPN which in my case created the order. Not a fix to the actual problem, but may save that embarassing phone call to your customer....