Loss of aircraft control on final approach?

[rhodges 6]

I don't quite know how to title this, but the following is what happened:Note: PFE/2000 ATC, ASA Weather, and FSC monitoring in FS9:I flew a flightplan from KIAD to OMDB with a cruise altitude of 33,000 feet with FMC control in the PSS 340-300 with no problem for over twelve hours. She nailed all planned headings, altitudes, and speeds on the money with no issues, UNTIL:Nearing final approach to RWY 12L, ATC ultimately directed me to descend to 2,000 feet, and put me on a good intercept heading for runway 12L. As normal. I was directed to contact the tower when I was on course.Everything went great until my gauges began to intercept the ILS and I tried to switch my autopilot from Hdg. control to Loc. control and let the autopilot take over for the intercept (I also tried the Appr. selection). Neither would engage nor would the indications light on the autopilot panel.From this point on I had no control of the aircraft no matter shat I tried. The plane held 2,000 feet and my current heading. The heading indicator, speed and altitude selections on the autopilot could be changed, but had no affect relative to climbing speed or heading changes. It was as if the autopilot was not engaged, or possibly better described, the altitude and heading was totally locked to their present configuration. I tried turning off the autopilot and autothrottle and flying manually. Same thing. No response on the controls. The aircraft would not bank and change headings, nor climb as I approached higher terrain from joystick movement (Yes, I checked to be sure it was enabled). I tried everything I could think of. In spot view, there was no movement of the control surfaces. No matter what I tried, the aircraft held the present heading and altitude, and oversped.It has been a long time since I flew this bird and the problem is probably a forgotten step or provision by this old memory. However, after a quick check of the manual and search on this forum, I am overlooking the cause and/or solution. Seems like this is something that was addressed litterally years ago, but senior moments take over when I try to remember what it was.If anyone knows my error, a reply sure would be appreciated.Thanks:RTH

[rhodges 6]

I think I found my mistake.In the FMC I selected the ILS frequency in the VOR section of the "RAD/NAV" options, but NOT in the "ILS/Freq" section. I tried a flight around the airport pattern at OMDB for RWY 12L and had the same problem. When I put the freq. in the right place, the slection lit up when pressed and I was then able to complete a normal ILS/Glideslope approach.However, this still does not explain why I could not disengage and control the aircraft with manually selected headings and altitudes in the autopilot, or have any affect on the controls in manual flight with the autopilot turned off on my previous approach. I was able to execute a missed approach on my pattern flight after I had engaged approach and begun my normal final approach on the glideslope *@ about 700 feet). Heading, Speed, and Altitude control were re-established with no problem.Sorry for the confusion.RTH