Cowon S9 doesn't work well when connected with USB.

[TheJas]

First of all I'd like to say that the device itself works just fine.
But as the title says when I connect with USB cable it doesn't work fine.
The transfers are slow (500-700 KB/S), sometimes it doesn't let me transfer at all(the device just ejects himself when I try to copy something), sometimes I even have to try hard so the device will be recognized in my PC, and Windows 7 (x64) ALWAYS tells me that my usb 2.0 device can run faster.
Note: It didn't work like that when I bought it, it worked fine while connected with usb for about a year and a half.
Does someone have a solution for me?

[CrowdAds]