Programs may be unable to access some network locations after you turn on User Account Control in Windows Vista or in Windows 7

http://support.microsoft.com/kb/937624

Important This workaround may make your system unsafe. Microsoft does not support this workaround. Use this workaround at your own risk.

To work around this problem, configure the EnableLinkedConnections registry value. This value enables Windows Vista or Windows 7 to share network connections between the filtered access token and the full administrator access token for a member of the Administrators group. After you configure this registry value, LSA checks whether there is another access token that is associated with the current user session if a network resource is mapped to an access token. If LSA determines that there is a linked access token, it adds the network share to the linked location. 

To configure the EnableLinkedConnections registry value, follow these steps:

1. Click Start, type regedit in the Start Search box, and then press Enter.
2. Locate and then right-click the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
3. Point to New, and then click DWORD Value.
4. Type EnableLinkedConnections, and then press Enter.
5. Right-click EnableLinkedConnections, and then click Modify.
6. In the Value data box, type 1, and then click OK.
7. Exit Registry Editor, and then restart the computer.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\NetworkProvider\

Set or create a DWORD

RestoreConnection = 0

If your Win7 is connected to a network or a domain and you experience a short interruption when logging on, this should fix the problem

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\NetworkProvider]
"Restore Connection"=dword:00000000

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\NetworkProvider\HwOrder]
"ProviderOrder"="RDPNP,LanmanWorkstation,webclient"

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\NetworkProvider\Order]
"ProviderOrder"="RDPNP,LanmanWorkstation,webclient"