Thanks for ur help. yes i have tried another lead.
I did what u said when battery went below 15% and after i switched it off for 30 minutes and unplugged from the wall socket but when i selected "update drivers" it came back with the message that the driver already installed were up to date and ok.
i am reluctant to uninstall the driver completely before i can find a trusted site where i can find and download exactly the same one again. can u help suggest how i do this?