Beats Audio software not working + laptop hangs during copying data from usb or external HD

I have recently bought hp envy 15 j028tx ( as written on the box, it is refurbished one) from the begining beats audio application was not working and i am not sure about the beats audio speaker, i have tried reinstalling software from recovery but that didnt help. Second issue is that laptop hangs only when i am copying data from external hard disk or usb and i am also doing some other regular stuff like browsing etc, it hangs in a way that it keeps on copying but touch pad stop working and after like 1,2 min it start working or if the copying process is completed it would start working. if i leave laptop while it is copying and do nothing then it do not get hang.
retailer told me that their are different categories (quality wise) of refurbished laptop. i have not seen category written any where on box or any other place but when i installed MSI afterburner, in information section it says model C, is that the same category thing.
please clearify this i am so confused.