Too many Tracks (nuendo4)

I have windows 8 and ssd. behringer 1820 + midas. but i have been getting this message with and with out midas… so when recording 8 and 10 tracks… yes and always when recording drums, and Always when i have just had a thought “maybe im hitting a bit too hard” then it cuts out the sound and keeps recording for a while then stops and gives out that message… i have tried to record no music with all 16 tracks (8 normal + adat) and its ok… what is going on, and how to fix this?
nuendo 4 + waves compleate. + win8 +ssd +16g RAM