I don’t know why the fix isn’t made available via windows update yet. This is a very wide spread problem where your VISTA machine which is using ICS. After a couple of hours vista looses conectivity. Some programs like Messenger, Skype, eMule, etc.. still work and other Systems using the shared connection also have connectivity.

SYMPTOMS

After you configure Internet Connection Sharing in Windows Vista, you may find that, although the network connection works correctly at first, the network connection stops working after one-to-two hours. For example, you may be unable to connect to the Internet, to other computers on the local area network (LAN), or to network resources on the LAN.

CAUSE

This problem occurs because of a bug in the WinSock bind() function.

RESOLUTION

Hotfix information

A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Website: http://go.microsoft.com/?linkid=6294451

And ofcourse restart is Required after the installation to finish applying the HOTFIX.