I ran across this article from Christopher Elliott:

Like every other airline, Delta is trying to cut its distribution costs by moving more of
its bookings to the Web. However, at the same time, it does not regard an Internet
reservation as being equal to a phone reservation or even one made through a travel
agent. (Delta isn't alone in this; I've had reports of other carriers, notably United,
ignoring its Web reservations in a similar way.)

The airline will ignore your e-mails and printouts if it's convenient - and you really
have nothing to fall back on. Delta's contract of carriage, which is its agreement
between the airline and passenger, makes no mention of online reservations. The
government's code of federal regulations doesn't address online purchases of this
kind either. Consumer laws regarding Internet buying vary from state to state.

Solution? Don't believe anything on an airline's Web site until you have secured
either: a) a record locator, which is a six-digit alphanumeric code unique to every
airline ticket; b) a written confirmation from your airline or travel agency, as either a paper ticket or a e-ticket itinerary; or c) proof from your credit card that your purchases went through.

Airlines like Delta apparently think the Web is a cool toy with which they can play
around with their customers and never get caught.

Wondering if anyone have experienced web booking problems where their reservations are not confirmed?

Don't become an airline's plaything.