Error Message "Can't Access X workgroup"

[#1]

I have tried to set up a wireless LAN between my desktop and laptop computers. But I am having difficulty getting them to "talk" to each other.  Both connections are excellent on both computers.  The only difference between the two computers is that on the laptop, when I view the workgroup computers, both computers show up on the laptop.  However, they don't show up on the desktop.  I also get an error message " Can't Access X workgroup, where X is the name I have assigned to the group.
Has anybody had this problem, and how do they get over it.

[#2]

It could be firewall related on your desktop, try turning any software firewall off and try it.
If it works you know that is your problem

[#3]

Thanks for your quick response adiewoo.
However, I thought that, so I set up the firewall profiles on both computers to be the same.  I have AVG Internet Security on both.

[#4]

Are they both in the same workgroup? Can you ping the other machine. What is the router on some routers you cant connect 2 wireless pc's without setting it up on the router