Serum plays chord without MIDI notes whenever arm recording is on.

Can someone help me?

I recently started using Ableton and tried mapping my MIDI Keyboard with Ableton.
I couldn't get it to work because mine isn't compatible.

However, I played a chord on the keyboard, and now, regardless of which track Serum is on, Serum plays automaticcly without MIDI notes whenever I have arm recording on.
I haven't selected any track, but Serum keeps playing that chord over my MIDI tracks, and I don't know how to get rid of it.

the problem isn't just with Serum; it happens with any instrument I load in Ableton. As soon as I press the red arm recording button and hit play, it automatically starts playing that chord.

Sounds like a MIDI controller or something is generating notes, try looking at restricting the MIDI input on the armed track until you find the source.