thank you so much, somehow the mode had moved from dma in primary channel to pio as current file transfer as you suggested, I uninstalled the devices and had windows reinstall on startup as suggested in the instruction link and it reset to dma. thankyou thankyou.
I am back to 20min burns! phew!
I had recently installed an application which may have conflicted and caused the change? anyhow have uninstalled that application (not needed) to secure against conflict.
once again thankyou for your quick response and great advice!