BleepingComputer.com: computer will not go online when coming back from turned off or stand by

Greetings-
When I try to go on the internet after my computer has been turned off or has been on standby for any length of time, it gets "stuck". I wind up having to restart it to get online. Even when I go off line and work with my desktop and then try to get back on the internet, it gets "stuck" again. My internet provider, AT&T, told me to delete my browser history and that worked for about a minute. Any thoughts or help would be greatly appreciated.
I have Norton 360 and I have run every scan it has and I have Tuneup 1-Click and have done the same there. This is installed in a Dell with the Windows XP Pro.

Thank You -

More then likely some of the services that provide may have went a bit...'crazy'. Do you connected to the net with a wireless adapter or by an ethernet cord? If by ethernet cord, restart these services:

DHCP Client
DNS Client
Windows Firewall/Internet Connection Sharing

If you are conencted by a wireless adapter:

Restart the services above
Wireless Zero Configuration
And if you use a third-party software to get you into the Internet, that service. For example, TP-Link users would restart the TP-Link Client Service (I hope you get what I mean).

Hope it helps.