Ever since moving to Cubase last year I've been plagued by the 'disk overload' error any time I do a realtime bounce, which is of course necessary when using any hardware.
For every hardware track I had to export the stem and reimport it as audio which was often a real pain and workflow killer.
Anyway, after a helpful post on another forum, i've finally found out how to fix it! Just ensure to leave a few bars of silence prior to your track starting!
I always left up to a bar of silence, but never more than that hence when I had never stumbled across the solution before.
For some reason Cubase must need that time to 'level out' before it starts its realtime bounce process.
I have more than enough CPU power and disk speed so I knew it couldn't/should't be that.