Windows 7: Cannot connect to shared folder or printer

I've got two Vista Ultimate computers. Both have the same username and password. Same workgroup name.

Password protected sharing is enabled on both.

I shared a folder on computer 1, and added Everyone to the security tab, with full control.

When i try to map the folder from computer 2, I can see computer 1 listed. But when I click on the + next to it, it asks for a username and password (which I did not expect to be necessary since they are both the same user account and password) and when I enter it it says Logon Unsuccessful.

Any ideas where to look?

Thanks

BTW when I connect in the other direction, from computer 1, I can see the shared folders on computer 2 and map the drive. It asked for a login the first time, after that it connects without asking.

I ran ipconfig and I see that they are showing different gateways. They are connected to wall jacks in an office building. But then, how am I file sharing in one direction if they are on different gateways?