USB HELP ME!!!

Hi, not to appear computer illliterate here but i really need some help.
i have just installed a few new programmes, one for a digital camera and one to play music… neither of wich seem to work.
for example when i turn on the music center the music will play and i can do most things… but when i connect the usb to the computer through the usb drives i have problems. firstly the computer asks me if i want to install the device found? this is odd as i have already installed it but then it flashes on and off repetativley untill i unplug the device. the same happens for my camera.

please can i have an answer to this question. i hope that i have come to the best people unlike those morons oin PC world. Thanks

–lew–