Hi
In general the more there is software that intertwines with the TCP/IP stack the more there is a chance that something will be corrupted.
Thus the Norton, Registry booster or ant other Network related "Magics" can be part of the problem rather than the remedies.\
Try this process.
Check carefully the computer for Viruses and Malwares.
If needed clean it up.
Then do, WinSock and TCP/IP Refresh.
Type Cmd in the Start Search text box.
Press Ctrl-Shift-Enter keyboard shortcut to run a Command Prompt as an Administrator. Allow elevation.
Type netsh winsock reset in the Command Prompt , and then press the Enter key.
Do the same process for refreshing the TCP/IP just replace the typed command with.
netsh interface ipv4 reset press Enter
netsh interface ipv6 reset press Enter
ipconfig /flushdns press Enter
Restart your Computer.
Still a problem?
Check the Router's support, and make sure that your using the latest firmware for the Router.
Check the Computer's manufacturer support site and make sure that you are using the latest Drivers.
If the support site has newer version of Drivers and the current installed Drivers claim to be the most updated Drivers use this method.
Download the Drivers and unpack them to a folder of your choice.
In the Device manger, right click on the adapter.
Click on Update Drivers, and choose the Browse my computer for drivers,
Choose let me pick from a list, Click on Have a Disk and point to the folder with the Drivers.