I, also, use an M-Audio KSP 88. I had a problem a long time ago with the midi out cable not plugging all the way in. The cable end was molded so that the pins were in the plug but the plastic barrel end would stop them short from going all the way in. So it caused the same intermittent problem you describe with your 49.
Might try checking that out.

Nifty9993 I'm not using a usb hub, both are straight into usb ports on the back of the pc,

still worth checking what else is sharing that usb hub/controller (internally) and that the power management is configured right

Thanks guys. I replaced the cable and so far all seems perfect so maybe it was as simple as that....time will tell.

One very strange thing I wanted to mention was I have my Blackstar Club HT40 under my desk and my PC sits at the side of the desk. I was recording today and I had finished tracking guitar and was moving on to keys. I had been setting the organ sound with the guitar still on my lap then when I was ready I put the guitar back on the stand and switched the amp off, standby first then main power. Went to the keyboard and began playing....nothing! No input from the keys. Switched my PC off and back on again, loaded the project and keyboard was back, working perfectly!!

There must be a voltage surge..,or some other technical term that I don’t know :) that knocks the keyboard or PC sideways!?!?
Now I’m not sure if I’ve done this in the past and that’s what my problem has actually been, or a combination of the two things....

Anyway, thought I’d just mention it.

Amp now has a note on “do not switch off! Keys!” :)

Cheers