While it's not a 'true' fix, a quick remedy than often works for me is to connect the phone to the PC via USB, and then reboot the phone while connected to said PC. Often the PC will then recognize the phone as a new device and attempt to install the correct drivers. (Check your carrier's forum for a possible true "fix")
I would install an older driver (I use Samsung's 1.4.6.0 driver), and once installed, connect the phone to your PC, but make sure the PC is disconnected from the Internet while connecting the two together, and then reboot the phone... this will force Windows to use the older driver, rather than search the Internet for the latest one. (Which seems to cause the PC recognition issues... at least for me, my PC, phone, ROM, etc. lol)
Hope this helps...