TR-8 jerky behaviour

[elastic]

Hi,

I have my TR-8 sync'd to ableton via midi. No usb connected. However, when i'm in ableton and a i press a key on my virus ti (my master keyboard), it forces the TR-8 to stop for a brief moment, which throws everything out of sync then.

the virus is connected via usb.
i should point out that this is only happening on an 'external instrument' track in ableton. It works fine on other normal midi tracks.

Any ideas as to what this could be?

Many thanks

Tom