I finally had to add something here. I'm also having a problem mounting my epic. Every time I get it to work (and I have the latest drivers, rebooted computer and phone, etc...) the next time I try to connect, I get a "device cannot start code 10 error". I unplug it, plug it into another USB port and it loads fine. Next time, if I use the same port, I get the same error again and have to change to another port. I'm friggin running out of ports!
I've deleted the drivers, used the Windows 7 X64 hardware wizard, started in Safe mode and deleted all samsung drivers, used Driver Detective, everything I can think of. I'm not a noob, so this is frustrating the heck outta me. I also make sure to "unmount" on the phone and "remove hardware, eject media" on the PC. I don't know if I want to kick the crap out of my computer or stomp on my phone!