Having similar problem for some machines (all XP not on Windows 7 though) can ping, but can't connect to shares or in our case Internet either. Everything running very slowly as well. Can't find out where it is yet and don't have time to research it properly yet. Need ot get it all working again and then maybe look at it. This is the second time (August 2012) that MS updates have caused a major problem. Just can not trust them anymore so will have to implement an agressive change control which is difficult in such a small department. We are not all big corporate IT departments.