Windows XP Networking

Have you set up a Small office network using Windows XP and sharing an Internet connection? Everything works fine, but then one fine day you wake up, and find out that the ICS not longer work. Funny thing is that I can still see the Host computer, shared files and print using the shared printer. The only thing that stops working is the actual internet sharing. Anybody experience this situation and care to discuss it?

Thanks!

Cesar