Sharing hard drives on my network

For the record, I tried the "search" funtion on the forum to find the answer to this question before asking. If I missed the answer, please feel free to send me the link as I'm sure this question has been asked before.

My wife and I have 2 Windows XP computers on a network through our Netgear router. When I right click on "Start" then hit "explore" I see "My Network Places." When I hit the + sign next to that I see "Entire Network." When I hit the + sign next to that I see "Microsoft Windows Network." when I hit the + sign next to that I see XXXXXX Network. The "XXXXXX" is my last name and the name of the network.

I assume this is the "tree" I follow to get access to my wife's hard drives. When I double click on the "XXXXXX" netowork, I get the following message:

"XXXXX network is not accessible. You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions.

The list of servers for this workgroup is currently not available."

Her computer is on, we've "dragged" files across the network in the past (but not recently), but why can I now not see her hard drives? She can't see mine either.

Advice? Thanks for your time in advance.