How to change your nic to half-duplex:

Windows 2000 or XP:

1. Open Control Panel.
2. Double-click Network and Dial-up Connections.
3. Identify the icon for your cable modem connection: usually Local Area Connection.
4. Right-click that icon and select Properties.
5. Under the ethernet adapter icon, click the button Configure.
6. Click the tab Advanced to bring it to the front:
7. In the Property box, the property name to be selected varies according to model of ethernet card. Examples are: Network Link Selection, Media Type, Connection Type, Duplex Mode, or any similarly-named property which can have Values looking like Auto-Negotiation, or 10BT, or 10BaseT.
8. In the Value box, select a value which either (a) explicitly says half-duplex or semi-duplex, or (b) at least does not say full-duplex [e.g. 10BaseT on its own is OK]. If there is a choice between 10 and 100 with half-duplex, choose the 10. Do not choose 10Base5, 10Base2, or AUI.
9. Click OK to exit the Adapter settings.
10. Click OK to exit the Connection properties.if u are using a router at set network card 100 full