Fix Problems With Copying Large Files in Windows Vista
 

If you've been having problems copying large files over mapped drives, network disconnects, or having to reboot your router a lot more often than normal, then you can try out this fix to solve the problem.

The problem stems from the new auto-tuning network, which changes the receive window on the fly. Thankfully we can easily turn it off from an administrative mode command prompt.

Open Administrative Mode Command Prompt

netsh int tcp set global autotuninglevel=disabled

http://www.howtogeek.com/howto/windo...windows-vista/