Had the same issue, see recent post today.
The router etc works perfectly on one machine, until you try to connect through it to another. if this is the case, then its the Antivirus software that is blocking packets.
Disable the Autoprotect and try that. I have my email scanning on auto, but not the PC.
The USB Pen drive, if you are using an extention cable that also sometimes needs its own drivers for some bizaar reason, you can get a universal one from Winfiles.com