I have a Springfield Defender 1911 National match .45 .Standard safety, standard beaver tail, no firing pin block, no aftermarket parts at all. Super crisp 5 lb trigger. Original as the day I bought it.  I was shooting it a day ago when it doubled. (two shots One trigger pull) It only did this once, and freaked me out. But I finished my box of ammo and put the gun away. I made a gunsmith appointment and it will be going into the shop next week but theres more problems. After cleaning the gun and doing a cycling to move the lube around the rails I placed the safety on and as usual performed a safety check. With no real exertion, the safety fell and the hammer dropped! Not to half cock, all the way! I cocked the hammer, engaged the safety and tried again. Safety fell and hammer fell again! Pulled out the trigger weight guage and its releasing the safety and dropping the hammer at 6.5 LBS.Now I'm not a gunsmith, but what could be causing this? My disconnector?The tip has a little wear but not any more than usual. This gun has been ultra reliable for over 8 years now. I've never had a complaint or problem with it. I was figuring on doing some upgrades after the holidays(beavertail, commander hammer, ambi safety)but now I 'm looking at an unsafe weapon. What part or parts could cause this malfunction? HELP!
Synweap223 Out!

I will assume that when you say safety, you are talking about the THUMB safety, not the grip safety.  With that said, it sounds like the engagement surface on the safety stud has developed an angle that allows the trigger bow to push down on the thumb safety.  This disengages the thumb safety just enough to let the trigger bow ride up and over the stud, which releases the sear and the hammer falls.  You might also want to check the front of the thumb safety where the detent rides, there is usually a bit of a hole where the detent can get some help locking the safety in the up position.

You mentioned that the gun had "doubled" on you.  This can be caused by a couple of things.  If the sear nose is too short, the hammer hooks can hit the sear and bounce the sear out of the way allowing the hammer to fall just after the slide goes into battery.  This can be aggravated by a sear spring that is just a touch light.  The only way the disconnector can have anything to do with this is if it is hanging up in its tunnel.  It doesn't need to move much in the tunnel, maybe 1/32", so try cleaning the tunnel with some Hoppes and a pipe cleaner.  
HTH
Vince

If you have shot the pistol a lot for 8 years something may now be worn.

There are separate safety tests for the thumb safety, grip safety, and disconnector functions that are too lengthy to post here.

You need to take your pistol to a good 'smith. Could be a problem with the thumb safety, sear, hammer, pin/hole wear, or the disconnector. The trigger group is easily replaced on a 45.

some additional info.

(1) Thumb safety blocks the sear. If your pistol fires with the safety on, you have too much play in the safety/sear or sear/hammer.
Also check the sear spring, its a flat spring under the mainspring housing. One of the legs operates the sear. If the spring is weak/broken you got problems.

(2) Grip safety blocks the trigger bow. Even with problem (1) your gun should not fire when the trigger is pulled if you are not touching the grip safety.

(3) Doubling or going full auto can be caused by an extreme case of (1) or a bad disconnector. If the disconnector becomes too short, usually at the top, then during firing, it will not move down enough to disconnect the trigger from the sear - you got full auto! This could also be caused by the weak sear spring preventing the sear from correctly engaging the hammer notch during the cocking phase.

After you correct your problems, when you decide to change to an ambi-safety this part needs to be fit correctly by a gunsmith.

Are you sure nobody has worked on your gun, maybe 'stoned' the sear?

Hope this helps, don't worry, its all fixable.

[:D]