It could be connection firewall issue or permission issue. To find out, use net view \\remotepcip. If you received system error 53, you my have connection firewall issue; if it is system error 5, you may have a permission issue. this troubleshooting may help,

troubleshooting is not accessible error When try to access a remote computer, you may receive the following error messages: "....is not accessible. You may not have permission to use this network ...
     www.howtonetworking.com/Troubleshooting/notaccessibale0.htm  

Bob Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN Troubleshooting on http://www.ChicagoTech.net 
How to Setup Windows, Network, VPN & Remote Access on http://www.HowToNetworking.com 
 I've started getting this message when I try to connect to another PC in
 my workgroup (which is home):

 Home is not accsssible. 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 network path was not found.

 And, I can't connect at all. Anyone got any ideas how to fix this silly
 thing?