I am a developer (using eclipse) and regularly have my Samsung Galaxy SII connected to my PC via a USB cable. A few times per day I will unplug the cable and plug it back in again in order to take phone calls, go to lunch etc. About 4 times out of 5 this is all fine. But one time in 5 the PC fails to properly re-communicate with my mobile and eclipse does not recognise the phone as being connected. Repeatedly unplugging and replugging in makes no difference, the connection is lost. The only way I know to fix it is to reboot my PC - which takes ages!... Is there something else I could try?
Sometimes my computer does the same thing, though it doesn't come up too often. In those cases, I try plugging the device into a different usb port. Usually it fixes the problem (though the first port is still 'disabled' for that particular device until I reboot).