A FOKKER 100 FLC HAD DIFFICULTY CTLING THE ACFT AFTER TRYING TO DISCONNECT THE AUTOPLT NEAR DAL.

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5 MI NE OF LOVE FIELD. AFTER REACTING TO A TCASII RA ON DOWNWIND TO RWY 13L; FO RE-ENGAGED THE AUTOPLT AND COMMENCED AN APCH. CTL DIRECTED L TURN TO 240 HDG. IN THE TURN; THE ACFT BEGAN A SHALLOW DSCNT. THE PF ATTEMPTED TO DISCONNECT THE AUTOPLT AND ROLL OUT. THE ACFT WOULD NOT ROLL OUT; SO THE FO ATTEMPTED ANOTHER DISCONNECT. HE GOT THE ACFT UNDER CTL AND WE REQUESTED A TURN TO FINAL AND LNDG CLRNC. APCH ASKED IF WE WANTED TO HAVE GND EQUIP STANDING BY AND WE ANSWERED AFFIRMATIVE. NO FURTHER PROBS WERE NOTED AND THE LNDG WAS UNEVENTFUL. FLT PARAMETERS WERE 2700 FT; 220 KIAS; AND 20 DEG BANK ANGLE. ADDITIONALLY; WE GOT A STABILIZER OUT-OF-TRIM AND A WINDSHEAR WARNING. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE PF BELIEVES THE FIRST ATTEMPT AT AUTOPLT DISCONNECT WAS UNSUCCESSFUL AND HE WAS FLYING AGAINST A STILL ENGAGED AUTOPLT. IT WASN'T UNTIL HE OBSERVED A STABILIZER TRIM MESSAGE THAT HE REALIZED THE AUTOPLT WAS TRIMMING AGAINST HIS INPUTS. THE AUTOPLT WAS CORRECTLY DISENGAGED AND THE ACFT FLEW NORMALLY.