Home network file shares only work one way

I am currently sharing folders on my home network between my desktop PC (Win 7 64) and laptop (Win 7 64), both going to the same switch (Zyxel G5-105B). I'm using the default Windows sharing, but I cannot access my desktop PC from my laptop. It works the other way, though. Here's the full run-through:

1. I can see my desktop PC (\\JUHA-PC\) in my desktop PC network locations and by opening it through Explorer, and I can see the currently shared folders
2. On my laptop (\\JUHA-LAPTOP\), I can also see the shared folders it has in both Network locations and through Explorer
3. Now, on my laptop, I can also see the desktop PC shared folders through Explorer \\JUHA-PC\, and I can transfer files just fine from my desktop to my laptop, but...
4. On my desktop PC, I cannot access the laptop at all. It is not visible in Network locations and I cannot access it through Explorer \\JUHA-LAPTOP\ (Windows throws the error: The network path was not found)

Running net share on either computer displays their respective shares like it should.

On both computers, under Advanced sharing settings, I have the following (identical) settings:

Home or Work profile
- Turn on network discovery
- Turn on file and printer sharing
- Turn on sharing so anyone with network access can read and write files in Public folders
- File sharing connections, use 128-bit encryption...
- Turn off password protected sharing - Allow Windows to manage homegroup connections

I'm running Comodo Firewall with pretty much identical settings on both computers.

File and Printer Sharing for Microsoft Networks is enabled on both computers' Local Area Connections.

So the question is, how can I get my desktop PC to access the shares on my laptop? As far as I know, it should work with these settings, especially since it already works the other way just fine?

Thanks!

Edit: I also tried the Map Network Drive method listed here:
http://answers.microsoft.com/en-us/windows/forum/windows_7-networking/windows-7-network-error-code-0x80070035-windows/84791143-b70a-4ec2-b700-98df657fe45c

With both the IP and the computer name, but it also would not connect. I also tried the usernames of both domains/workgroups. No connection.