Strange MIDI loop sending Cutoff and notes continuously

I used couple soft synth- sessional drummer, Rapture and Elastic. I do not freez them right away. The input to Soft Synth MIDI track is from Roland Fantom G. I can not have both MIDI In and Out connected because when 2 MIDI cables are connected, something sends Cutoff and notes continuously. It sends it to all tracks assigned to Fantom. Not happening on any other tracks. I did not know what is going on, but then thought- it must be comming from soft synth because when I close this particular song, it stops. But it makes no sense. Ok, the soft synth is not freezed (is there such word? Or shell I say- frozen?), but it should play without sending anything to Fantom. The Soft Synth Out is set to- well- soft synth itself. It goes to Rapture. The Fantom is only Input. Why is it getting data from software? Thanks.

I am slightly confused about that button. It used to be always on when you select the track in earlier Sonar versions. As you pointed out, it not supposed to do anything other than repeating signal from MIDI In. If I play 3 notes on Fantom and input them to the software, they would return to Fantom (Local Off on Fantom) and trigger the Fantom's sound module. All I should hear are 3 notes I played. I shoul not hear 3 notes playing repeatedly over and over with Cutoff going from 0 to 127. There is nothing to send these data to Fantom- all I play is 3 notes. Now the Soft synth (Rapture) set to be triggered by Fantom on Input. The Output is to Rapture- not to Fantom. If Softsynth sends the data, how it gets back to Fantom? I have Yamaha connected- it does not receive the data. The question is- how the Softsynth Cutoff is programmed? Is there a step sequencer? Lets say I play 1 note and hear filter (Cutoff) open and close. Somebody programmed the sound to do that and it appears that it comming through Input back to Fantom or distributed to other MIDI tracks. I made shure I do not set the Fantom input to "All" or "Omni" I set it to "Delta 1010 Midi In 1". How is it possibly getting any MIDI data from the softsynth (if it comming from softsynth).  

Thank you for trying to figure it out at this time of the night. The Cutoff is active when it is not used on Fantom- I see it triggered going up and down and notes repeat itself. Soon as I unplug one of the cables, it stops. Me and a partner together have about 40 years of MIDI experience and we don't get it. Also- the cake keeps changing Sonar- I can not get the feel of it. The set up is simple.

Roland Fantom as MIDI controller. Soft synth Raprure In- Delta 1010 Midi, Out- Rapture. Audio- In- Rapture, Out- Master.

That is working fine.

I create new track and want to use Fantom G for its onboard sounds. I set Local Off on Fantom. Midi In- Delta 1010, Midi Out- Delta 1010. It is very simple. It should receive note from keyboard trough Delta input, record notes in Sonar and play them back through Delta Out back to Fantom to trigger onboard sound module of Fantom. Soon as I play one note, the loop starts- it looks like arpeggiator, when there is no arpeggiator and Cutoff going up and down. It affects Sinfle and Multy/Studio (multytrack) mode.

I know what switch you talking about, I was told earlier in the day to set it to off.

Also there is some weirdness about Midi Slave mode- I am confused between MTC (Midi Time Machine) and MIDI Slave- appears as Fantom do not respond to clock in MIDI Slave state, but it all gets massed up with the loop, so I can not tell what is going on. I would say- it comes from soft synth, and yes, I have the button "Thru" on on every chennel that is active- does it send the data to all tracks? Without that "thru" button on Sonar track no sound can be triggered from anything- I would say- it must be active.

I dont see how I can record anything with Echo Off. There will be no signal comming back to Fantom and I will not have playback. The ONLY track that supposed to send any data to Fantom is the track that set to Delta Out (To Fantom MIDI IN). The Softsynth set to send data to Rapture on Out. Fantom set to Input on few tracks that set to Soft Synth on Output. The only track that set to Fantom OUT is the one I am trying to use. Nothing else sends out assigned to Delta/Fantom. All other outs set to Rapture or Sessional Drummer.

I will test it again. I only have 1 track sending OUT MIDI data to Fantom. It set to Delta In and Out from and to Fantom. No other tracks send to Fantom. I do not remember muting the Soft Synth, but I did close that particular song and loop disapeared, which tells me that it is the soft synth. I do not know how they program sounds for Rapture. If I knew how they make filters open and close for individual sound, I would understand where it comming from. I suspect that if I change sound on Raprure, the loop might disapear, but I did not try it yet. Thanks for the ideas.

The only thing I can think of trying at this point is to see if using MIDIOx to check what's passing through which MIDI ports throws any light on things. It might be worth checking the events list as well if you've not already done so.

Other than that I've no suggestions at the moment. The one time I've seen something that resembles your description it was when I'd accidentally set up a MIDI feedback loop, but your problem may well be something quite different of course.