No net connectivity

I am having Windows Vista Ultimate sp2 ......... i am having a network conection which lets me work on the internet but does not connect to the local network in fact the icon of internet connectivity shows that i am not even connected to my modem but i am still connected to the internet....... the network and sharing centre does not show my other laptop which is connected to the same modem ..... i can see my PC in that laptop but i can't access it the error that comes is : "Check the spelling of the name. Otherwise, there might be a problem with your network. To try to identify and resolve your network problems, click Diagnose.  Error code: 0x80070035 The network path was not found. "
Please I need Serious help!!!! =(