one more try from here. sounds like the usb driver is messed up and won't recorrect itself. uninstall the usb driver, reboot pc. make sure you have internet connection on pc (windows will try to query the internet for the driver if it can't find one on hard drive), plug in epic, select mass storage, wait for the prompts, wait for the device install (notice in system try the device installing icon, wait for message that says device is ready for use. the wait could take a few minutes.
that's all i can do from here. i know that some people said to download the drivers from samsung befitting your windows OS (vista, win7, 64-bit, etc.), but i never had to do that with my vista laptop. worked the first time (with the prep and wait times above).
good luck.