COMPUTER GLITCH CAUSES ERRONEOUS GND SPD READOUT FOR ARTCC RDP.

Narrative

ZDV HANDED OFF AN MD80 TO MY SECTOR. THE MD80 WAS LEVEL AT FL240. MY STRATUM WAS FL270 TO FL999. ZDV HANDED OFF THE A6 AT FL250 TO THE SECTOR BELOW ME. THE MD80 WAS REQUESTING FL330. BOTH ACFT HAD RTES ULTIMATELY CONVERGING FROM A NW DIRECTION TO A SE DIRECTION. ALL INVOLVED SECTORS WERE FULLY AWARE OF THE TFC AND SIT. I WAS TRAINING ON THE RADAR SIDE AND THE MD80 WAS IN FRONT BY 6 OR 7 MI AT AN AIRSPD OF 450 KTS. THE A-6 WAS INDICATING AN INCREASING SPD FROM 320-380 KTS. AT APPROX 6.8 MI I DOUBLE-CHKED THE ACFT SPDS; EVEN CHKING THE FILED FLT PLANS. THE A-6 FILED 420 KTS; THE MD80 FILED 437 KTS WINDS WERE OUT OF THE NW AT 50 KTS. I DEEMED SEPARATION SUFFICIENT AND CLBED THE MD80 TO FL330. MY INSTRUCTOR STILL WAS NOT COMFORTABLE SO I TURNED THE MD80 15 DEGS R AWAY FROM THE A-6 STILL IN-TAIL. THE A-6 CONTINUED IN SPD ULTIMATELY TO 500 KTS AND CAUGHT THE MD80. INVESTIGATION SHOWED THE A-6 WAS FLYING AT 490-500 KTS ALL THE WAY. OUR COMPUTER 'GLITCHED' WHEN THE ZDV CTLR STARTED A 'TRACK MESSAGE' ON THE A-6 PRIOR TO HDOF. THE ZAB COMPUTER THEREFORE BEGAN 'SEARCHING' FOR THE 'NEW TRACK.' IN DOING SO; IT LOST THE ACTUAL SPD OF THE A-6 AND THEN BEGAN TRACKING AND BUILDING UP TO THE ACTUAL SPD. THE COMPUTER HISTORY SHOWED ZAB SPD READOUT GOING FROM 420 KTS TO 120 KTS; 140 KTS; ETC; UNTIL REACHING 500 KTS. I CLBED THE MD80 WHEN THE SPD INDICATED 380 KTS.