This Microsoft knowledgebase article may help.
They recommend two methods:
Method 1: Manually enable flow control in the transmit (Tx) and receive (Rx) directions
To manually enable flow control for the Gigabit network connection,
follow these steps:
- Click Start, type ncpa.cpl in the Start Search box, and then click ncpa.cpl in the Programs list.
- If you are prompted for an administrator password or confirmation, type the password, or click Continue.
- Right-click the Gigabit network connection, and then click Properties.
- If you are prompted for an administrator password or confirmation, type the password, or click Continue.
- On the Networking tab, click Configure.
- On the Advanced tab, click the flow control property that is in the Property box.
- In the Value drop-down menu, select the value that enables flow control in the Tx and Rx directions(select the Rx & Tx Enabled option
if it is available), and then click OK.
and
Method 2: Change the link speed to 100 Mbps Full Duplex
To change the link speed to 100 Mbps Full Duplex, follow these steps:
- Click Start, type ncpa.cpl in the Start Search box, and then click ncpa.cpl in the Programs list.
- If you are prompted for an administrator password or confirmation, type the password, or click Continue.
- Right-click the Gigabit network connection, and then click Properties.
- If you are prompted for an administrator password or confirmation, type the password, or click Continue.
- On the Networking tab, click Configure.
- On the Advanced tab, click the property that is in the Property box.
- In the Value drop-down menu, select the value that represents the 100 Mbps Full Duplex setting, and then click OK.
Another suggestion Microsoft gives is to check the network bandwidth:
Media Center Extender responds slowly when I am using it.
This can be due to a low amount of available network bandwidth, or the Windows
Media Center computer might be running low on available system
resources.
To test your connection, use the Network Performance Tuner.
To use the Network Performance Tuner in Windows Media Center
- Start the Media Center Extender device.
- On the start screen on the Media Center Extender, scroll to Tasks, and then select tune network.
- Follow the steps in the Network Performance Tuner to determine if there is enough available bandwidth on your home network.