A319 Captain reports slats locked during approach with numerous secondary automation failures that should not have occurred. ECAM and QRH procedures were complied with and an uneventful landing ensued.

Narrative

On final approach upon selecting landing gear down; several ECAM procedures were displayed along with their associated aural alerts. On the Captains PFD; USE MAN PITCH TRIM was displayed briefly. As the pilot flying; I continued the approach while trying to assess the situation. The First Officer remarked that during the initial cautions; the DIRECT LAW ECAM procedure was displayed for a short period of time. He also remarked that several ECAM procedures were subsequently displayed in rapid succession; but could not recall what they were as they were rapidly changing. Eventually; the following ECAM procedures were displayed: F/CTL-SLATS LOCKED; Wing tip brakes on; AUTO FLT-AUTO THRUST OFF; Thrust levers move. A go-around was executed at approximately 1500 AFE (best guess) after coordinating with tower and addressing the auto thrust loss. Instructions were received from tower to a specified heading (southerly) and to maintain 3000 FT. The decision was made to execute a go-around because of reduced slat extension; and the required adjustment to the landing distance (8000 feet in length). During the go-around; the gear was raised; but the flaps were not moved for the obvious reason. The slats were positioned between the first and second dot in amber (QRH FLAPS=3: SLATS between 1 and 3) Upon gear extension; with subsequent cautions/warnings; all of the following were lost: Autopilot (attempts were made by me to engage both autopilots-one at a time- while on approach as well as later on during the flight) Auto Thrust (same as above). On both PFD's the following displays were lost: Flight Directors; all speed reference displays on the speed tape (F Speed; Green Dot; VFE next; Overspeed Warning; VREF; and Stall Warning). There were no X's to indicate direct law; but neither were there whiskers. Since there was no flight director guidance during the go-around; I maintained 10 to 20 KTS above the selected speed of 150 KTS. After established at 3000 FT; I called for ECAM actions. The procedure was accomplished and cleared; and the status page was checked (there was nothing on the STS page other than normal indications). I then directed the First Officer to check for any follow up items in the QRH; which led us to F/CTL SLATS LOCKED. At this point I made the decision to transfer aircraft control; and assigned the communication and flying duties to him. The QRH procedures were followed; and the new approach speed calculated; as well as applying the new landing distance. Up to this point; the information we had relayed to approach control was that we were working on a flight control problem. After accomplishing the QRH procedures; I gave the controller the required information; declared an emergency; and requested the emergency equipment. Shortly thereafter; I briefed the crew and passengers that we would be making a normal landing. I also briefed them that the emergency equipment would be present; not to be alarmed; and that we would be taxing to the gate. (As a footnote and to weigh all my options; I checked twice to see if any FCC lights were illuminated; and preformed a light test; while considering a computer reset to recover the autopilot etc. to avoid Direct Law when the gear was lowered. I referenced the QRH; which states that when resetting a computer in-flight; as a general rule; the crew must restrict computer resets to those listed in the Computer Reset Table. I chose not to attempt a reset (not in reset table) in the event that doing so would compound the situation with unknown results. Additionally; I felt comfortable with the aircraft in its current configuration. I then took over as pilot flying and directed the First Officer to review the QRH procedures I had accomplished as a backup; and then to reference the ECAM Supplemental Manual. A call to operations was then made; and an ACARS message was sent. Satisfied that we had thoroughly and correctly accomplished all the SOPs we then made preparationsfor the approach. Longest runway was chosen. A 15-mile final was requested; and the gear was lowered early to prepare for Direct Law in the event that it occurred. It did not; and a Flaps 3 hand flown visual approach was made to a normal touchdown with Auto Brakes on MED. Flaps were not retracted during taxi in. Maintenance conferred with Maintenance Control; tests were run; the aircraft was powered down; the flaps/slats were cycled several times; the condition could not be duplicated; there was no history; and the aircraft was released for flight. The condition did not reoccur during the next flight. The obvious question is how a SLATS LOCKED condition resulted in the loss of the other components listed above. In my opinion; this should be reported to Airbus Industries to see if there is a software problem that caused this condition to occur. Had weather conditions not been ideal; a divert may have been required in order to execute a hand flown approach to CAT 1 minimums.