Used Galaxy S3 and S2 for two months no problem with Kies, then suddenly stopped recognising USB although it did charge both phones.
Spoken to Orange for 2 x hours and Samsung for 1 x hour and problem still unresolved.
However, if this solution works for anyone else, Samsung may have a sneaky way of getting you to part with your cash.
1. The phones stopped working with the USB cables supplied after an Android update was installed on both phones.
2.Orange and Samsung suggested that the computers may be faulty!!!!!!!!
3. unplug the USB cable from the S3 mains charger....the one with the two shiny ends.
4. open Kies and use this USB cable. The two phones suddenly connected no problem.
5. Speaking to an IT engineer, he said that this cable seems to have a voltage limiter unlike normal universal USB cables which seems very odd.
6. Both phones now connect everytime with this cable so try it for yourselves. If it works, why are Samsung saying nothing or is it a way to get you to purchase extra 'shiny' voltage limiting cables.
Million thanks!
I got a S3 LTE (brand new) and have the same problem. It took me 4 days (more than 15 working hours) to find the fix. Finally, it turn out to be the USB cable came with the phone package. It once worked, but only for a few times. Then it totally failed. Never thought of this can happen.
For reader who don't understand, the case is that when the phone connect to PC, it will be charging by USB but no device was detected by the PC. No any setting in the PC and phone can be done. I've installed USB drivers, Kies, uninstall and reinstall, set phone MTP+ADB, debug mode on/off etc. Still, no device can be seen.
As the USB cable was brand new from the package and at the first time I connected the USB cable to PC, it can show "new device found" but cannot be identified. So I thought it should be driver problem and do all kinds of installation I can find but no use.
Finally, I used the micro USB cable my wife was using and the phone is now connected to PC properly!