oop's i think i did it!

I just bought 3 new mp3 players,after trying them all,they didn't work,there was a proplem installing your(RCA....it might not work properly)!!! didn't work @ all,so called 3 diffent company's,got the same answer;plug into another win machine,they all work;so after having Dell fish around 4 hours all driver are there,there answer as always,reformat your drive!.However i think it was/is a tweak i did 2 the registry,so i thought i might send it out here & see if anybody might know what i did,because i just can't remember & it's a big registry!,thax in advance all answers welcome