Inserting soft synths & plugins


I never had this problem before, but with Platinum I'm finding that every time I insert a soft synth or plugin for midi such as Real Guitar or String Section etc. It just plays these two notes over and over and it's driving me nuts because I cannot find how to stop it. It's like a water torture but with sound!

Sometimes when I click the icon next to the name in the track view it will stop but as soon as I return to the track which has the synth or plugin as the output it starts again - usually I end up just converting the track to audio so I can work with that instead, but the downside is I'm not getting the midi sound I want before converting. Any idea what's causing this? Thanks!
If you record with that track, are those random notes showing up in the midi data? If they are, it would be the midi device/controller. If not, it's a glitch. If the midi controller and audio interface are on USB try a different usb port. Reinstalling Platinum can't hurt either.
Thanks - yes they do show up in the midi data. So what now? I have been into Preferences/midi playback and the only way I could stop it was to uncheck the 'Always echo current midi track' box but then I found I couldn't produce any sound at all, even from the keyboard. Any suggestions? Thanks a lot.
If it's really playing over and over, it sounds like you're looping. Is there a yellow line at the top that demarks the start and end of a loop?

Do they show up in the midi data of a brand new midi track? Before you've recorded anything?

So many questions!
What are you using for MIDI-- e.g., a MIDI keyboard controller connected using a simple MIDI-to-USB adapter, etc.? And if you're indeed using a MIDI-to-USB adapter, what brand is it? The cheap ones are prone to failures, bad data transmission, etc. I saw a post once-- don't remember if it was at HR or a different forum-- where someone posted a screenshot from the MIDI-OX utility that showed two oddball MIDI note messages being received over and over. Based on the regular clockwork timing of the messages and the data I could tell that they were supposed to be the Timing Clock and Active Sensing messages, but one of the bits was apparently getting dropped by the bad cable. Try checking your DAW's MIDI Monitor mode, or else use a utility such as MIDI-OX, to see if you're getting two messages over and over again like clockwork. If so, post a screenshot of them. Also, try a different MIDI-to-USB cable.