Let's try a couple of fixes.
Disable the DHCP Broadcast Flag:
Link:
http://support.microsoft.com/default.aspx/kb/928233
1. Go to Start and type in "regedit" (without the quotes) and press Enter.
2. Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\{GUID}
In this registry path, click the (GUID) subkey that corresponds to the network adapter that is connected to the network.
3. On the Edit menu, point to New, and then click DWORD (32-bit) Value.
4. In the New Value #1 box, type DhcpConnDisableBcastFlagToggle, and then press ENTER.
5. Right-click DhcpConnDisableBcastFlagToggle, and then click Modify.
6. In the Value data box, type 1, and then click OK.
7. Close Registry Editor.
NOTE: You should do this for each and every GUID subkey.
TCP/IP stack repair options for use with Windows Vista.
Start, Programs\Accessories and right click on Command Prompt, select "Run as Administrator" to open a command prompt.
Reset WINSOCK entries to installation defaults:
netsh winsock reset catalog
Reset IPv4 TCP/IP stack to installation defaults.
netsh int ipv4 reset reset.log
Reset IPv6 TCP/IP stack to installation defaults.
netsh int ipv6 reset reset.log
Reboot the machine.