I figured my problem out. There was another post that was made on this site that discussed a LAN autodisconnect registry setting. I followed the following link to microsofts web-site which discusses how to resolve this problem. Here's the link:
http://support.microsoft.com/default.asp...%3E%3C/table%3E
By simply going to the command prompt and typing the following, the registry was updated so that the machines would no longer time out:
net config server /autodisconnect:-1
This has fixed my problem thus far, machines no longer lose internet access intermittently. I am wondering if the Symantec update may have fiddled with this registry setting?
Hope this post helps somebody.