(Unsolved) Intermitant Noise from Ti

[Ref54]

Hi all, i'm new on the forum.

I bought a Ti(1) keyboard last week to replace my Kb. Unfortunately it has a problem. Every so often the sound from the patch (single or multi) I'm playing cuts out and I get a really bad sound coming out. If I keep playing, this strange noise coughs and splutters for ages.

Here's the weird thing; if I hook-up my Kb to the Ti via midi, The problem is identical on both synths at the exact same time. The Kb is not affected if they're not joined by midi.

My synths are used as stand alone keyboards and not connected to a computer. My first thought was that it was a mains power problem, but I have changed mains sockets and used another power cord but the problem is still there. The Ti doesn't have the most recent OS and I'm wondering if updating would solve it???

I would be grateful for any help.
Regards
Derek.

My gear is for live shows and as it stands at the moment, the Ti is useless.