XP Pro failed sharing

I have a small network with two XP Pro PC's and one Win98 PC. They are connected through a switch. For troubleshooting purposes, they are not connected to the internet and there is no firewall software installed or turned on. File sharing is turned on, on all three. The My Documents folder is full shared without a passord on all three. I have used different ethernet cables and different ethernet ports to eliminate hardware problems. I have used different NIC's on the one problem XP Pro PC. All three show up on the network, but the one XP Pro denies access to it's shared folder. From the Win98 PC the error is that the network is busy. It can be pinged. I used the home network wizard to set it up. When attached to the cable modem, they can all reach the internet. The XP Pro PC that fails to share, can access the shares on the other PC's. So, What is blocking sharing on the one XP Pro? Is there something about the user account that could be the problem?

 

I tried sharing a new folder with no luck. I'm open to more suggestions.

 

The guest account is enabled, although it's not enabled on the other XP PC that works ok. Thanks again.

 

Is simple file sharing turned on (windows explorer, tools, folder options, view, advanced options, bottom item)?

 

I'll check back with you Monday. Thanks

 

It was Norton

On a hunch I tried disabling Norton AV 2005, but it didn't help. So I uninstalled it and full networking and sharing returned right away. I replaced Norton with CA's AV that comes in Microsoft's Partnerpack.
Thanks for the previous help.