I had 2 computers connected through a router and on a home network. I never had any problems seeing the other computer. My wife's computer died and I had to reinstall it.

Now I cannot see her's and it will not show that it is on the network.

I have run the wizard, checked windows firewall settings, checked the router settings and am now just baffled.

Any ideas of where to go from here?

Did you add the new box as a trusted site? Try shutting off the firewall (briefly) and pinging.

I will try that, but it has the same IP on the router the old box had.

If the ping works with the firewall off, then you know the firewall is the problem. Try sharing a directory from the new pc, then see if the other pc can mount the shared directory. I would manually add both pcs to the trusted sites list on each pc also.

Problem is...I can't even see the other computer. I can see mine on hers but hers doesn't show up in the network computers.

Mine is still giving me hell as well. I tried everything in the books with no luck. However all of a sudden out of the blue, It allowed me to access and view all files in the other computers yesterday from the laptop. Then I try it this morning and I no longer have access/permission. That is without rebooting either computer or making any changes, whatsoever. Its happened before and makes no sense at all.........

If home networking, you have to have file and print sharing enabled and actually share something (drive, directory, etc) on all computers on your network for them to show up and be accessed.

I did that. I set hers up with the same workgroup as mine and mine shows up on hers, but hers will not show up on mine. Hers shows me in the workgroup, but not hers.

I don't F&%#%^g get it All day yesterday and this morning I was able to access everything on my network. I rebooted my laptop and I can no longer access any of the other computers. I can see them but have lost permission to open the directories. I have not changed any of my boot options, I just simply rebooted and lost access. Any ideas???????????

completely uninstall/remove sharing and the workgroup from both computers (including the "trusted computer" rule from the firewall) and then start again.
Some of the setting in sharing are toggles and a new instantance of the same computer (as in a reinstall) sometimes confuses it.